NEET (UG) · 2020

NEET 2020, question by question

Which chapter each question came from, how the paper was spread, and how to solve each one. Keep the official paper open beside this page.

Sit this paper free All years, chapter-wise

Summary

The heaviest chapters in each subject, and how the questions were spread by level. One year is not a forecast.

Botany
45 Q
1. Principles of Inheritance and Variation4
2. Cell Cycle and Cell Division4
3. Molecular Basis of Inheritance4
0 easy · 45 medium · 0 hard
Zoology
45 Q
1. Biotechnology: Principles and Processes6
2. Animal Kingdom4
3. Biomolecules4
0 easy · 45 medium · 0 hard
Chemistry
45 Q
1. p-Block Elements3
2. Thermodynamics3
3. Hydrocarbons3
0 easy · 45 medium · 0 hard
Physics
45 Q
1. Optics4
2. Electronic Devices4
3. Electrostatics4
0 easy · 45 medium · 0 hard

Chapters

Every chapter asked, and the NCERT chapters to read for it.

Biotechnology: Principles and Processes6
Class 12: Biotechnology: Principles and Processes
Animal Kingdom4
Class 11: Animal Kingdom
Biomolecules4
Class 11: Biomolecules
Evolution4
Class 12: Evolution
Human Health and Disease3
Class 12: Human Health and Disease
Structural Organisation in Animals3
Class 11: Structural Organisation in Animals
Human Reproduction3
Class 12: Human Reproduction
Biotechnology and its Applications3
Class 12: Biotechnology and its Applications
Reproductive Health2
Class 12: Reproductive Health
Breathing and Exchange of Gases2
Class 11: Breathing and Exchange of Gases
Digestion and Absorption2
No matching NCERT chapter
Excretory Products and their Elimination2
Class 11: Excretory Products and their Elimination
Body Fluids and Circulation2
Class 11: Body Fluids and Circulation
Chemical Coordination and Integration2
Class 11: Chemical Coordination and Integration
Strategies for Enhancement in Food Production1
No matching NCERT chapter
Neural Control and Coordination1
Class 11: Neural Control and Coordination
Locomotion and Movement1
Class 11: Locomotion and Movement

Questions

Tap Explain on any question for a short summary and our full working.

Botany questions, each with its chapter and our explanation
Q	Chapter and topic	NCERT	Kind and level
1	Organisms and PopulationsPopulation attributes	Class 12: Organisms and Populations	Single correctMedium
A medium single correct question on population attributes, from Organisms and Populations. NCERT: Class 12: Organisms and Populations Sex ratio, natality (birth rate) and mortality (death rate) describe a population. Interactions such as competition, predation and mutualism take place between different species, so they belong to a community rather than to one population.
2	Plant Growth and DevelopmentGrowth phases	Class 11: Plant Growth and Development	Single correctMedium
A medium single correct question on growth phases, from Plant Growth and Development. NCERT: Class 11: Plant Growth and Development In the sigmoid growth curve, growth is slow in the lag phase, fastest in the log (exponential) phase, and slows in the stationary phase. Senescence and dormancy are not periods of active growth.
3	Morphology of Flowering PlantsRoot, stem and leaf	Class 11: Morphology of Flowering Plants	Single correctMedium
A medium single correct question on root, stem and leaf, from Morphology of Flowering Plants. NCERT: Class 11: Morphology of Flowering Plants In monocots such as wheat, the primary root is short-lived and is replaced by a large number of roots arising from the base of the stem; these make up the fibrous root system.
6	Principles of Inheritance and VariationDeviations from Mendelism	Class 12: Principles of Inheritance and Variation	Single correctMedium
A medium single correct question on deviations from mendelism, from Principles of Inheritance and Variation. NCERT: Class 12: Principles of Inheritance and Variation Iᴬ and Iᴮ produce slightly different forms of sugar on the red cell surface; when present together each expresses its own sugar (codominance). The other statements are correct: gene I has three alleles, a diploid person carries two of them, and allele i produces no sugar.
8	Principles of Inheritance and VariationGenetic disorders	Class 12: Principles of Inheritance and Variation	Single correctMedium
A medium single correct question on genetic disorders, from Principles of Inheritance and Variation. NCERT: Class 12: Principles of Inheritance and Variation Sickle-cell anaemia is an autosomal recessive disorder of the β-globin gene, which lies on chromosome 11. Haemophilia is X-linked recessive, phenylketonuria autosomal recessive, and thalassemia autosomal recessive.
12	Sexual Reproduction in Flowering PlantsMegasporogenesis	Class 12: Sexual Reproduction in Flowering Plants	StatementsMedium
A medium statements question on megasporogenesis, from Sexual Reproduction in Flowering Plants. NCERT: Class 12: Sexual Reproduction in Flowering Plants Pollen grains (male gametophyte) inside the anther (sporophyte), and the embryo sac (female gametophyte) inside the ovule (sporophyte), each hold one generation within the other.
13	Mineral NutritionNitrogen metabolism	No matching NCERT chapter	Single correctMedium
A medium single correct question on nitrogen metabolism, from Mineral Nutrition. NCERT: No matching NCERT chapter Nitrogenase reduces N₂ to ammonia and releases hydrogen as a by-product: N₂ + 8e⁻ + 8H⁺ + 16ATP → 2NH₃ + H₂ + 16ADP + 16Pi.
14	Cell Cycle and Cell DivisionMitosis	Class 11: Cell Cycle and Cell Division	Single correctMedium
A medium single correct question on mitosis, from Cell Cycle and Cell Division. NCERT: Class 11: Cell Cycle and Cell Division In G₁ the cell is metabolically active and grows but does not replicate its DNA. DNA replicates in the S phase, and nuclear division happens in the M phase.
16	Cell: The Unit of LifeProkaryotic and eukaryotic cells	Class 11: Cell: The Unit of Life	Single correctMedium
A medium single correct question on prokaryotic and eukaryotic cells, from Cell: The Unit of Life. NCERT: Class 11: Cell: The Unit of Life Inclusion bodies store reserve material, such as phosphate, cyanophycean and glycogen granules, and lie free in the cytoplasm without a membrane. They play no part in taking in food particles.
17	Cell: The Unit of LifeCell organelles	Class 11: Cell: The Unit of Life	Single correctMedium
A medium single correct question on cell organelles, from Cell: The Unit of Life. NCERT: Class 11: Cell: The Unit of Life The Golgi apparatus is the important site of formation of glycoproteins and glycolipids.
20	Morphology of Flowering PlantsFlower and fruit	Class 11: Morphology of Flowering Plants	Single correctMedium
A medium single correct question on flower and fruit, from Morphology of Flowering Plants. NCERT: Class 11: Morphology of Flowering Plants The ray florets of sunflower are epigynous: the ovary is inferior.
23	Microbes in Human WelfareIndustrial and sewage applications	Class 12: Microbes in Human Welfare	Single correctMedium
A medium single correct question on industrial and sewage applications, from Microbes in Human Welfare. NCERT: Class 12: Microbes in Human Welfare After secondary treatment, most of the activated sludge is pumped into anaerobic sludge digesters, where anaerobic bacteria digest it and produce biogas.
28	Mineral NutritionEssential elements and their functions	No matching NCERT chapter	MatchingMedium
A medium matching question on essential elements and their functions, from Mineral Nutrition. NCERT: No matching NCERT chapter Iron is required for chlorophyll biosynthesis, zinc for the synthesis of auxin (IAA), boron for pollen germination, and manganese for the photolysis of water: (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i).
29	Anatomy of Flowering PlantsSecondary growth	Class 11: Anatomy of Flowering Plants	Single correctMedium
A medium single correct question on secondary growth, from Anatomy of Flowering Plants. NCERT: Class 11: Anatomy of Flowering Plants Sapwood is the outer, peripheral part of the secondary xylem; it is lighter in colour and conducts water. The inner, dark heartwood no longer conducts water but gives mechanical support.
32	Biodiversity and ConservationPatterns of biodiversity	Class 12: Biodiversity and Conservation	Single correctMedium
A medium single correct question on patterns of biodiversity, from Biodiversity and Conservation. NCERT: Class 12: Biodiversity and Conservation Robert May's global estimate puts the number of species at about 7 million; about 1.5 million species have been described.
33	Molecular Basis of InheritanceTranscription and translation	Class 12: Molecular Basis of Inheritance	Single correctMedium
A medium single correct question on transcription and translation, from Molecular Basis of Inheritance. NCERT: Class 12: Molecular Basis of Inheritance Translation begins with the activation of amino acids and their attachment to their cognate tRNAs, the charging or aminoacylation of tRNA.
34	Biodiversity and ConservationPatterns of biodiversity	Class 12: Biodiversity and Conservation	Single correctMedium
A medium single correct question on patterns of biodiversity, from Biodiversity and Conservation. NCERT: Class 12: Biodiversity and Conservation The largely tropical Amazonian rain forest has the greatest biodiversity on Earth.
36	Anatomy of Flowering PlantsAnatomy of root, stem and leaf	Class 11: Anatomy of Flowering Plants	StatementsMedium
A medium statements question on anatomy of root, stem and leaf, from Anatomy of Flowering Plants. NCERT: Class 11: Anatomy of Flowering Plants Scattered, conjoint and closed vascular bundles with bundle sheaths, a large parenchymatous ground tissue and no phloem parenchyma are features of the monocot stem.
40	Transport in PlantsWater movement in plants	No matching NCERT chapter	Single correctMedium
A medium single correct question on water movement in plants, from Transport in Plants. NCERT: No matching NCERT chapter Guttation, the loss of liquid water from leaf tips at night and early morning, happens when root pressure pushes water up while transpiration is low.
41	Organisms and PopulationsInteractions	Class 12: Organisms and Populations	Single correctMedium
A medium single correct question on interactions, from Organisms and Populations. NCERT: Class 12: Organisms and Populations Plants produce chemicals such as nicotine, caffeine, quinine and strychnine as defences against grazers and browsers.
42	Photosynthesis in Higher PlantsPhotorespiration	Class 11: Photosynthesis in Higher Plants	Single correctMedium
A medium single correct question on photorespiration, from Photosynthesis in Higher Plants. NCERT: Class 11: Photosynthesis in Higher Plants When RuBisCO binds O₂, RuBP forms one molecule of phosphoglycerate (a 3-carbon compound) and one of phosphoglycolate (a 2-carbon compound), instead of two molecules of PGA.
48	Microbes in Human WelfareIndustrial and sewage applications	Class 12: Microbes in Human Welfare	MatchingMedium
A medium matching question on industrial and sewage applications, from Microbes in Human Welfare. NCERT: Class 12: Microbes in Human Welfare Clostridium butylicum gives butyric acid; Trichoderma polysporum gives the immunosuppressant cyclosporin A; Monascus purpureus gives statins, which lower blood cholesterol; Aspergillus niger gives citric acid: (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii).
50	Plant KingdomAlgae	Class 11: Plant Kingdom	Single correctMedium
A medium single correct question on algae, from Plant Kingdom. NCERT: Class 11: Plant Kingdom Red algae store food as floridean starch, which is very similar to amylopectin and glycogen in structure.
52	Cell Cycle and Cell DivisionMeiosis	Class 11: Cell Cycle and Cell Division	MatchingMedium
A medium matching question on meiosis, from Cell Cycle and Cell Division. NCERT: Class 11: Cell Cycle and Cell Division Homologous chromosomes pair (synapsis) in zygotene, cross over in pachytene, show chiasmata in diplotene, and the chiasmata terminalise in diakinesis: (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i).
53	Plant KingdomAlgae	Class 11: Plant Kingdom	Single correctMedium
A medium single correct question on algae, from Plant Kingdom. NCERT: Class 11: Plant Kingdom NCERT names Chlorella and Spirulina as unicellular algae, rich in protein and used as food supplements. Laminaria and Sargassum are large brown algae, Gelidium and Gracilaria are multicellular red algae, and Volvox is colonial.
56	Environmental IssuesOzone depletion	No matching NCERT chapter	Single correctMedium
A medium single correct question on ozone depletion, from Environmental Issues. NCERT: No matching NCERT chapter The Montreal Protocol, signed in 1987 and effective from 1989, controls the emission of ozone-depleting substances such as CFCs.
57	Biological ClassificationViruses and lichens	Class 11: Biological Classification	Single correctMedium
A medium single correct question on viruses and lichens, from Biological Classification. NCERT: Class 11: Biological Classification Viroids, found by T.O. Diener as the cause of potato spindle tuber disease, are free RNA without the protein coat that viruses have.
58	Morphology of Flowering PlantsFlower and fruit	Class 11: Morphology of Flowering Plants	Single correctMedium
A medium single correct question on flower and fruit, from Morphology of Flowering Plants. NCERT: Class 11: Morphology of Flowering Plants In perigynous flowers such as plum, rose and peach, the other floral parts arise from the rim of the thalamus at about the level of the ovary, so the ovary is half inferior. Brinjal and mustard have superior ovaries and sunflower an inferior one.
60	EcosystemEnergy flow	Class 12: Ecosystem	MatchingMedium
A medium matching question on energy flow, from Ecosystem. NCERT: Class 12: Ecosystem Grass is the producer (first level), the rabbit a herbivore (second), the crow a primary carnivore (third) and the vulture a top carnivore (fourth): (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i).
61	Principles of Inheritance and VariationMendelian genetics	Class 12: Principles of Inheritance and Variation	Single correctMedium
A medium single correct question on mendelian genetics, from Principles of Inheritance and Variation. NCERT: Class 12: Principles of Inheritance and Variation Mendel chose seven characters, each with two contrasting traits, so he selected 14 true-breeding pea varieties as pairs.
63	Sexual Reproduction in Flowering PlantsPollination and outbreeding devices	Class 12: Sexual Reproduction in Flowering Plants	Single correctMedium
A medium single correct question on pollination and outbreeding devices, from Sexual Reproduction in Flowering Plants. NCERT: Class 12: Sexual Reproduction in Flowering Plants Water hyacinth and water lily flowers emerge above the water, and NCERT notes they are pollinated by insects or wind, as in most land plants; not all aquatic plants are water-pollinated.
64	Plant Growth and DevelopmentPlant hormones	Class 11: Plant Growth and Development	Single correctMedium
A medium single correct question on plant hormones, from Plant Growth and Development. NCERT: Class 11: Plant Growth and Development Gibberellins elongate the internodes; spraying them on sugarcane lengthens the stem and raises the yield by as much as 20 tonnes per acre.
65	Photosynthesis in Higher PlantsLight reaction	Class 11: Photosynthesis in Higher Plants	Single correctMedium
A medium single correct question on light reaction, from Photosynthesis in Higher Plants. NCERT: Class 11: Photosynthesis in Higher Plants Plastoquinone is a mobile carrier that takes electrons from photosystem II to the cytochrome b₆f complex; plastocyanin then carries them on to photosystem I.
66	Plant Growth and DevelopmentSeed germination and differentiation	Class 11: Plant Growth and Development	Single correctMedium
A medium single correct question on seed germination and differentiation, from Plant Growth and Development. NCERT: Class 11: Plant Growth and Development Abscisic acid, phenolic acid and para-ascorbic acid are inhibitors that keep seeds dormant. Gibberellic acid does the opposite: it breaks dormancy and promotes germination.
67	Molecular Basis of InheritanceTranscription and translation	Class 12: Molecular Basis of Inheritance	Single correctMedium
A medium single correct question on transcription and translation, from Molecular Basis of Inheritance. NCERT: Class 12: Molecular Basis of Inheritance In transcription, RNA polymerase binds the promoter and itself opens the DNA helix as it moves along; a separate helicase unwinds DNA in replication.
69	EcosystemProductivity and decomposition	Class 12: Ecosystem	Single correctMedium
A medium single correct question on productivity and decomposition, from Ecosystem. NCERT: Class 12: Ecosystem NPP = GPP − R, where R is the energy plants use in respiration. Since R is always positive, gross primary productivity is always more than net primary productivity.
71	Plant KingdomBryophytes and pteridophytes	Class 11: Plant Kingdom	Single correctMedium
A medium single correct question on bryophytes and pteridophytes, from Plant Kingdom. NCERT: Class 11: Plant Kingdom In some pteridophytes such as Selaginella and Equisetum, the sporophylls are grouped into compact structures called strobili or cones. Salvinia and Pteris bear sporangia without cones, and Marchantia is a liverwort.
72	Cell Cycle and Cell DivisionMitosis	Class 11: Cell Cycle and Cell Division	Single correctMedium
A medium single correct question on mitosis, from Cell Cycle and Cell Division. NCERT: Class 11: Cell Cycle and Cell Division Cells that do not divide further exit the G₁ phase and enter the quiescent stage, G₀, where they stay metabolically active but do not proliferate.
74	Molecular Basis of InheritanceDNA structure	Class 12: Molecular Basis of Inheritance	Single correctMedium
A medium single correct question on dna structure, from Molecular Basis of Inheritance. NCERT: Class 12: Molecular Basis of Inheritance Length = number of base pairs × distance between them = 6.6 × 10⁹ × 0.34 × 10⁻⁹ m = 2.244 m, about 2.2 metres.
77	Molecular Basis of InheritanceDNA structure	Class 12: Molecular Basis of Inheritance	Single correctMedium
A medium single correct question on dna structure, from Molecular Basis of Inheritance. NCERT: Class 12: Molecular Basis of Inheritance In the double helix, adenine forms two hydrogen bonds with thymine, and guanine forms three with cytosine.
83	Principles of Inheritance and VariationLinkage and recombination	Class 12: Principles of Inheritance and Variation	Single correctMedium
A medium single correct question on linkage and recombination, from Principles of Inheritance and Variation. NCERT: Class 12: Principles of Inheritance and Variation Sutton and Boveri proposed the chromosomal theory of inheritance; Thomas Hunt Morgan and his colleagues verified it experimentally with Drosophila, leading to the discovery of linkage.
85	Respiration in PlantsKrebs cycle	Class 11: Respiration in Plants	Single correctMedium
A medium single correct question on krebs cycle, from Respiration in Plants. NCERT: Class 11: Respiration in Plants In one turn of the citric acid cycle, only the conversion of succinyl-CoA to succinic acid makes a GTP (ATP) directly: one substrate-level phosphorylation.
86	Cell Cycle and Cell DivisionMeiosis	Class 11: Cell Cycle and Cell Division	Single correctMedium
A medium single correct question on meiosis, from Cell Cycle and Cell Division. NCERT: Class 11: Cell Cycle and Cell Division The synaptonemal complex forms in zygotene; in diplotene it dissolves, and the homologues begin to separate except at the chiasmata.
88	Sexual Reproduction in Flowering PlantsMegasporogenesis	Class 12: Sexual Reproduction in Flowering Plants	Single correctMedium
A medium single correct question on megasporogenesis, from Sexual Reproduction in Flowering Plants. NCERT: Class 12: Sexual Reproduction in Flowering Plants The funicle attaches the ovule to the placenta, and the hilum is the region where the body of the ovule fuses with the funicle. The chalaza is the basal part opposite the micropyle.
90	Environmental IssuesOzone depletion	No matching NCERT chapter	Single correctMedium
A medium single correct question on ozone depletion, from Environmental Issues. NCERT: No matching NCERT chapter The cornea absorbs UV-B radiation, and a high dose of it inflames the cornea, causing snow-blindness; ozone depletion over the Antarctic lets more UV-B through.

Zoology questions, each with its chapter and our explanation
Q	Chapter and topic	NCERT	Kind and level
4	Human Health and DiseasePathogens and diseases	Class 12: Human Health and Disease	MatchingMedium
A medium matching question on pathogens and diseases, from Human Health and Disease. NCERT: Class 12: Human Health and Disease Typhoid is caused by Salmonella typhi, pneumonia by Streptococcus pneumoniae and Haemophilus influenzae, filariasis by Wuchereria, and malaria by Plasmodium: (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii).
5	Reproductive HealthART	Class 12: Reproductive Health	Single correctMedium
A medium single correct question on art, from Reproductive Health. NCERT: Class 12: Reproductive Health In ZIFT a zygote or early embryo (up to 8 blastomeres) is transferred into the fallopian tube, and in IUT an embryo with more than 8 blastomeres into the uterus. GIFT transfers a gamete (ovum), and ICSI injects a sperm into an ovum in the laboratory.
7	Biotechnology: Principles and ProcessesRestriction enzymes and vectors	Class 12: Biotechnology: Principles and Processes	Single correctMedium
A medium single correct question on restriction enzymes and vectors, from Biotechnology: Principles and Processes. NCERT: Class 12: Biotechnology: Principles and Processes DNA ligase joins DNA fragments. Polymerases synthesise DNA, nucleases break phosphodiester bonds rather than separate the strands, and it is endonucleases, not exonucleases, that cut at specific positions within DNA; exonucleases remove nucleotides from the ends.
9	Animal KingdomNon-chordate phyla	Class 11: Animal Kingdom	MatchingMedium
A medium matching question on non-chordate phyla, from Animal Kingdom. NCERT: Class 11: Animal Kingdom Locusta is a gregarious pest; Asterias (an echinoderm) has radially symmetrical adults and bilaterally symmetrical larvae; scorpions breathe through book lungs; Ctenoplana, a ctenophore, shows bioluminescence: (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii).
10	Human Health and DiseasePathogens and diseases	Class 12: Human Health and Disease	Single correctMedium
A medium single correct question on pathogens and diseases, from Human Health and Disease. NCERT: Class 12: Human Health and Disease Plasmodium enters the human body as sporozoites through the bite of an infected female Anopheles mosquito. Gametocytes develop later in human blood and are taken up by the mosquito.
11	BiomoleculesCarbohydrates, lipids and nucleic acids	Class 11: Biomolecules	Single correctMedium
A medium single correct question on carbohydrates, lipids and nucleic acids, from Biomolecules. NCERT: Class 11: Biomolecules Inulin, a polymer of fructose, has glycosidic bonds; insulin, a protein, has peptide bonds. Cholesterol, glycerol and lecithin are lipid-related molecules with neither kind of bond as required.
15	Structural Organisation in AnimalsAnimal tissues	Class 11: Structural Organisation in Animals	Single correctMedium
A medium single correct question on animal tissues, from Structural Organisation in Animals. NCERT: Class 11: Structural Organisation in Animals The proximal convoluted tubule is lined by simple cuboidal brush-border epithelium, whose microvilli increase the surface for reabsorption. The intestine is lined by columnar epithelium.
18	Biotechnology: Principles and ProcessesrDNA technology	Class 12: Biotechnology: Principles and Processes	Single correctMedium
A medium single correct question on rdna technology, from Biotechnology: Principles and Processes. NCERT: Class 12: Biotechnology: Principles and Processes DNA fragments on the gel are stained with ethidium bromide and seen as bright orange bands under ultraviolet radiation.
19	Breathing and Exchange of GasesTransport of gases	Class 11: Breathing and Exchange of Gases	Single correctMedium
A medium single correct question on transport of gases, from Breathing and Exchange of Gases. NCERT: Class 11: Breathing and Exchange of Gases In the alveoli, low H⁺ concentration (together with high pO₂, low pCO₂ and lower temperature) favours the formation of oxyhaemoglobin. A higher H⁺ concentration favours its dissociation, as in the tissues.
21	Biotechnology: Principles and ProcessesRestriction enzymes and vectors	Class 12: Biotechnology: Principles and Processes	Single correctMedium
A medium single correct question on restriction enzymes and vectors, from Biotechnology: Principles and Processes. NCERT: Class 12: Biotechnology: Principles and Processes EcoRI recognises 5'-GAATTC-3' paired with 3'-CTTAAG-5', a sequence that reads the same on both strands in the 5'→3' direction. GGATCC is the site of BamHI.
22	Biotechnology: Principles and ProcessesRestriction enzymes and vectors	Class 12: Biotechnology: Principles and Processes	Single correctMedium
A medium single correct question on restriction enzymes and vectors, from Biotechnology: Principles and Processes. NCERT: Class 12: Biotechnology: Principles and Processes Statements (1) to (3) describe restriction enzymes, (1) in NCERT’s own words: each inspects the length of a DNA sequence, cuts at palindromic sites, and is a basic tool of genetic engineering. Statement (4) is about DNA ligase rather than restriction enzymes, which is how NTA’s final key comes to treat it as the odd one out.
24	Breathing and Exchange of GasesMechanism and regulation of breathing	Class 11: Breathing and Exchange of Gases	StatementsMedium
A medium statements question on mechanism and regulation of breathing, from Breathing and Exchange of Gases. NCERT: Class 11: Breathing and Exchange of Gases Inspiration begins with contraction of the diaphragm and of the external intercostal muscles, which increases the thoracic and pulmonary volume and lowers the intra-pulmonary pressure below atmospheric pressure.
25	Structural Organisation in AnimalsCockroach morphology and anatomy	Class 11: Structural Organisation in Animals	Single correctMedium
A medium single correct question on cockroach morphology and anatomy, from Structural Organisation in Animals. NCERT: Class 11: Structural Organisation in Animals The nervous system of the cockroach is spread through the body: the head holds only a small part of it, and the rest runs along the ventral side as a chain of ganglia, so the headless insect can survive for some days.
26	Animal KingdomChordate classes	Class 11: Animal Kingdom	StatementsMedium
A medium statements question on chordate classes, from Animal Kingdom. NCERT: Class 11: Animal Kingdom In vertebrates the notochord is present only in the embryo, and chordates have a dorsal, hollow nerve cord. In urochordates the notochord is only in the larval tail, and the subphyla of Chordata are Urochordata (Tunicata), Cephalochordata and Vertebrata; Hemichordata is a separate phylum.
27	Biotechnology: Principles and ProcessesRestriction enzymes and vectors	Class 12: Biotechnology: Principles and Processes	MatchingMedium
A medium matching question on restriction enzymes and vectors, from Biotechnology: Principles and Processes. NCERT: Class 12: Biotechnology: Principles and Processes Bacillus thuringiensis gives Cry proteins; Thermus aquaticus the thermostable DNA polymerase used in PCR; the Ti plasmid of Agrobacterium tumefaciens is a cloning vector; and the first recombinant DNA was made with a plasmid of Salmonella typhimurium: (a)-(iv), (b)-(iii), (c)-(i), (d)-(ii).
30	BiomoleculesEnzymes	Class 11: Biomolecules	MatchingMedium
A medium matching question on enzymes, from Biomolecules. NCERT: Class 11: Biomolecules Malonate competitively inhibits succinic dehydrogenase; collagen is a protein with peptide bonds; chitin forms the cell wall of fungi; ricin is a secondary metabolite (a toxin): (a)-(ii), (b)-(iv), (c)-(iii), (d)-(i).
31	Human ReproductionGametogenesis	Class 12: Human Reproduction	Single correctMedium
A medium single correct question on gametogenesis, from Human Reproduction. NCERT: Class 12: Human Reproduction The secondary oocyte completes its second meiotic division only when a sperm enters it at fertilisation, forming the second polar body and the ovum (ootid).
35	Biotechnology and its ApplicationsHuman insulin and vaccine production	Class 12: Biotechnology and its Applications	Single correctMedium
A medium single correct question on human insulin and vaccine production, from Biotechnology and its Applications. NCERT: Class 12: Biotechnology and its Applications The A and B chains of insulin are linked by disulphide bridges, not hydrogen bonds. Insulin is made as proinsulin with an extra C-peptide, and recombinant insulin is produced in E. coli.
37	Animal KingdomChordate classes	Class 11: Animal Kingdom	MatchingMedium
A medium matching question on chordate classes, from Animal Kingdom. NCERT: Class 11: Animal Kingdom Cyclostomes have 6–15 pairs of gill slits; cartilaginous fishes have a heterocercal tail; bony fishes have an air bladder; Trygon, the sting ray, has a poison sting: (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i).
38	EvolutionOrigin of life	Class 12: Evolution	Single correctMedium
A medium single correct question on origin of life, from Evolution. NCERT: Class 12: Evolution As NCERT describes it, Miller passed an electric discharge through a closed flask containing CH₄, H₂, NH₃ and water vapour at 800 °C and found amino acids formed.
39	EvolutionEvidences of evolution	Class 12: Evolution	Single correctMedium
A medium single correct question on evidences of evolution, from Evolution. NCERT: Class 12: Evolution Karl Ernst von Baer observed that embryos never pass through the adult stages of other animals, which disapproved the embryological support for evolution proposed by Ernst Haeckel.
43	Biotechnology and its ApplicationsBt crops	Class 12: Biotechnology and its Applications	Single correctMedium
A medium single correct question on bt crops, from Biotechnology and its Applications. NCERT: Class 12: Biotechnology and its Applications The cry genes of Bacillus thuringiensis code for insecticidal proteins, so Bt cotton resists insect pests such as the bollworms.
44	EvolutionEvidences of evolution	Class 12: Evolution	StatementsMedium
A medium statements question on evidences of evolution, from Evolution. NCERT: Class 12: Evolution Herbicide-resistant weeds, drug-resistant organisms and breeds of domesticated animals made by humans all arose from human action. Darwin's finches arose by natural adaptive radiation.
45	Human Health and DiseaseImmunity	Class 12: Human Health and Disease	Single correctMedium
A medium single correct question on immunity, from Human Health and Disease. NCERT: Class 12: Human Health and Disease Active immunity is slow and takes time to give its full response; it is passive immunity, with ready-made antibodies, that acts at once.
46	Strategies for Enhancement in Food ProductionAnimal breeding	No matching NCERT chapter	Single correctMedium
A medium single correct question on animal breeding, from Strategies for Enhancement in Food Production. NCERT: No matching NCERT chapter Hisardale was developed in Punjab by cross-breeding Bikaneri ewes with Marino rams: superior males of one breed mated with superior females of another.
47	Digestion and AbsorptionHuman digestive system	No matching NCERT chapter	Single correctMedium
A medium single correct question on human digestive system, from Digestion and Absorption. NCERT: No matching NCERT chapter The ileum is the highly coiled part of the small intestine and opens into the large intestine. The serosa is the outermost layer of the gut wall, and the appendix arises from the caecum.
49	Excretory Products and their EliminationRegulation and disorders	Class 11: Excretory Products and their Elimination	Single correctMedium
A medium single correct question on regulation and disorders, from Excretory Products and their Elimination. NCERT: Class 11: Excretory Products and their Elimination Glucose (glycosuria) and ketone bodies (ketonuria) in urine indicate diabetes mellitus. Uremia is urea in the blood and renal calculi are kidney stones; neither is a sign of diabetes in urine.
51	Reproductive HealthSTDs	Class 12: Reproductive Health	Single correctMedium
A medium single correct question on stds, from Reproductive Health. NCERT: Class 12: Reproductive Health Gonorrhoea, syphilis and genital herpes are all sexually transmitted. Malaria and filariasis are spread by mosquitoes, and cancer is not an infection.
54	Human ReproductionMenstrual cycle	Class 12: Human Reproduction	Single correctMedium
A medium single correct question on menstrual cycle, from Human Reproduction. NCERT: Class 12: Human Reproduction Rising estrogen from the growing follicle brings on the mid-cycle LH surge, and the LH surge induces ovulation. Of the options, only a high estrogen level leads to ovulation; LH and FSH are high, not low, at ovulation.
55	Biotechnology and its ApplicationsGene therapy	Class 12: Biotechnology and its Applications	MatchingMedium
A medium matching question on gene therapy, from Biotechnology and its Applications. NCERT: Class 12: Biotechnology and its Applications Bt cotton carries a Bacillus thuringiensis gene; ADA deficiency was the first disease treated by gene therapy; RNAi is a cellular defence in eukaryotes; PCR detects HIV in suspected AIDS patients: (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii).
59	Digestion and AbsorptionDigestion of food	No matching NCERT chapter	Single correctMedium
A medium single correct question on digestion of food, from Digestion and Absorption. NCERT: No matching NCERT chapter Enterokinase, secreted by the intestinal mucosa, converts inactive trypsinogen into active trypsin, which then activates the other pancreatic proenzymes. Pepsinogen is activated by HCl.
62	Neural Control and CoordinationSense organs	Class 11: Neural Control and Coordination	MatchingMedium
A medium matching question on sense organs, from Neural Control and Coordination. NCERT: Class 11: Neural Control and Coordination The organ of Corti lies on the basilar membrane; the cochlea is the coiled part of the labyrinth; the Eustachian tube connects the middle ear to the pharynx; the stapes is attached to the oval window: (a)-(iv), (b)-(ii), (c)-(i), (d)-(iii).
68	Excretory Products and their EliminationRegulation and disorders	Class 11: Excretory Products and their Elimination	Single correctMedium
A medium single correct question on regulation and disorders, from Excretory Products and their Elimination. NCERT: Class 11: Excretory Products and their Elimination Aldosterone makes the distal parts of the tubule reabsorb Na⁺ and water, which cuts urine output. Too little ADH causes diuresis, ANF causes vasodilation and opposes the renin–angiotensin mechanism, and less renin means less aldosterone.
70	Human ReproductionMale and female reproductive systems	Class 12: Human Reproduction	MatchingMedium
A medium matching question on male and female reproductive systems, from Human Reproduction. NCERT: Class 12: Human Reproduction The placenta secretes hCG; the zona pellucida is a layer around the ovum; bulbo-urethral glands secrete a fluid that lubricates the penis; Leydig cells secrete androgens: (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i).
73	EvolutionEvidences of evolution	Class 12: Evolution	Single correctMedium
A medium single correct question on evidences of evolution, from Evolution. NCERT: Class 12: Evolution The flippers of penguins and dolphins are analogous organs: similar in function but of different ancestry, the result of convergent evolution.
75	Body Fluids and CirculationECG	Class 11: Body Fluids and Circulation	Single correctMedium
A medium single correct question on ecg, from Body Fluids and Circulation. NCERT: Class 11: Body Fluids and Circulation In an ECG, the P-wave is depolarisation of the atria, the QRS complex depolarisation of the ventricles, and the T-wave ventricular repolarisation.
76	Body Fluids and CirculationBlood composition	Class 11: Body Fluids and Circulation	MatchingMedium
A medium matching question on blood composition, from Body Fluids and Circulation. NCERT: Class 11: Body Fluids and Circulation Eosinophils release histaminase and destructive enzymes; basophils release granules with histamine; neutrophils are phagocytic; lymphocytes carry out the immune response: (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i).
78	Biotechnology: Principles and ProcessesRestriction enzymes and vectors	Class 12: Biotechnology: Principles and Processes	Single correctMedium
A medium single correct question on restriction enzymes and vectors, from Biotechnology: Principles and Processes. NCERT: Class 12: Biotechnology: Principles and Processes The origin of replication (ori) is where replication starts, and it also controls the copy number of the linked DNA. A selectable marker picks out transformants; a recognition site is where a restriction enzyme cuts.
79	BiomoleculesProteins and amino acids	Class 11: Biomolecules	Single correctMedium
A medium single correct question on proteins and amino acids, from Biomolecules. NCERT: Class 11: Biomolecules Lysine has an extra amino group in its side chain, which makes it basic. Glutamic acid is acidic, valine is neutral, and tyrosine is aromatic.
80	Chemical Coordination and IntegrationHormonal disorders	Class 11: Chemical Coordination and Integration	MatchingMedium
A medium matching question on hormonal disorders, from Chemical Coordination and Integration. NCERT: Class 11: Chemical Coordination and Integration Too little ADH from the posterior pituitary causes diabetes insipidus; an overactive thyroid causes Graves' disease; too little adrenal cortical hormone causes Addison's disease; too little insulin from the pancreas causes diabetes mellitus: (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii).
81	Chemical Coordination and IntegrationEndocrine glands	Class 11: Chemical Coordination and Integration	Single correctMedium
A medium single correct question on endocrine glands, from Chemical Coordination and Integration. NCERT: Class 11: Chemical Coordination and Integration Glucocorticoids such as cortisol stimulate gluconeogenesis. Glucagon raises blood sugar (hyperglycaemia), insulin lowers it (hypoglycaemia), and insulin acts mainly on hepatocytes and adipocytes, not pancreatic cells.
82	BiomoleculesProteins and amino acids	Class 11: Biomolecules	Single correctMedium
A medium single correct question on proteins and amino acids, from Biomolecules. NCERT: Class 11: Biomolecules Collagen is the most abundant protein in the animal world; RuBisCO is the most abundant protein in the whole biosphere.
84	Locomotion and MovementSkeletal system	Class 11: Locomotion and Movement	MatchingMedium
A medium matching question on skeletal system, from Locomotion and Movement. NCERT: Class 11: Locomotion and Movement The last two pairs of ribs (floating ribs) do not connect with the sternum; the acromion articulates with the clavicle; the scapula lies on the back between the second and seventh ribs; the glenoid cavity receives the head of the humerus: (a)-(iv), (b)-(iii), (c)-(i), (d)-(ii).
87	Animal KingdomBasis of classification	Class 11: Animal Kingdom	Single correctMedium
A medium single correct question on basis of classification, from Animal Kingdom. NCERT: Class 11: Animal Kingdom Flatworms (Platyhelminthes) are bilaterally symmetrical and acoelomate. Ctenophores are radially symmetrical, aschelminthes pseudocoelomate, and annelids coelomate.
89	Structural Organisation in AnimalsAnimal tissues	Class 11: Structural Organisation in Animals	Single correctMedium
A medium single correct question on animal tissues, from Structural Organisation in Animals. NCERT: Class 11: Structural Organisation in Animals Goblet cells of the alimentary canal are unicellular glands: specialised columnar epithelial cells that secrete mucus.

Chemistry questions, each with its chapter and our explanation
Q	Chapter and topic	NCERT	Kind and level
91	Chemical Bonding and Molecular StructureMolecular orbital theory	Class 11: Chemical Bonding and Molecular Structure	Single correctMedium
A medium single correct question on molecular orbital theory, from Chemical Bonding and Molecular Structure. NCERT: Class 11: Chemical Bonding and Molecular Structure He₂ has four electrons: σ1s² σ*1s², so its bond order is (2 − 2)/2 = 0 and it does not exist. Li₂, C₂ and O₂ have bond orders of 1, 2 and 2.
92	EquilibriumSolubility product	Class 11: Equilibrium	Single correctMedium
A medium single correct question on solubility product, from Equilibrium. NCERT: Class 11: Equilibrium With solubility s in 0.1 M NaOH, [Ni²⁺] = s and [OH⁻] ≈ 0.1 M (the common ion). Ksp = s × (0.1)² = 2 × 10⁻¹⁵, so s = 2 × 10⁻¹³ M.
93	p-Block ElementsGroup 14 elements	No matching NCERT chapter	StatementsMedium
A medium statements question on group 14 elements, from p-Block Elements. NCERT: No matching NCERT chapter Solid CO₂ (dry ice), not the gas, is the refrigerant, so (a) is wrong. C₆₀ has twenty six-membered and twelve five-membered rings, so (b) is wrong. ZSM-5 converts alcohols into gasoline, and CO is a colourless, odourless gas: (c) and (d) are correct.
94	ThermodynamicsEntropy and Gibbs energy	Class 11: Thermodynamics	Single correctMedium
A medium single correct question on entropy and gibbs energy, from Thermodynamics. NCERT: Class 11: Thermodynamics ΔrG° = −RT ln K = −8.314 J mol⁻¹ K⁻¹ × 300 K × ln(2 × 10¹³). A large K gives a negative ΔrG°.
95	HydrocarbonsAromatic hydrocarbons	Class 11: Hydrocarbons	Single correctMedium
A medium single correct question on aromatic hydrocarbons, from Hydrocarbons. NCERT: Class 11: Hydrocarbons Side-chain chlorination of toluene in light gives benzal chloride, C₆H₅CHCl₂, which hydrolyses at 373 K to benzaldehyde: the gem-diol formed loses water to give the aldehyde.
96	Classification of Elements and PeriodicityModern periodic table	Class 11: Classification of Elements and Periodicity in Properties	StatementsMedium
A medium statements question on modern periodic table, from Classification of Elements and Periodicity. NCERT: Class 11: Classification of Elements and Periodicity in Properties Unununnium is element 111, roentgenium; darmstadtium is element 110 (ununnilium). The others match: 101 mendelevium, 103 lawrencium, 106 seaborgium.
97	Solid StatePacking in fcc, bcc and hcp	No matching NCERT chapter	Single correctMedium
A medium single correct question on packing in fcc, bcc and hcp, from Solid State. NCERT: No matching NCERT chapter In a bcc cell the atoms touch along the body diagonal, so √3 a = 4r and r = (√3/4) × a = (√3/4) × 288 pm.
98	Chemical Bonding and Molecular StructureDipole moment and Fajans' rule	Class 11: Chemical Bonding and Molecular Structure	Single correctMedium
A medium single correct question on dipole moment and fajans' rule, from Chemical Bonding and Molecular Structure. NCERT: Class 11: Chemical Bonding and Molecular Structure Trigonal planar BF₃, linear BeF₂ and CO₂, and para-dichlorobenzene are symmetric, so their bond dipoles cancel. NH₃, H₂O, NF₃, HF and 1,3-dichlorobenzene all have dipole moments.
99	ElectrochemistryElectrochemical cells	Class 12: Electrochemistry	Single correctMedium
A medium single correct question on electrochemical cells, from Electrochemistry. NCERT: Class 12: Electrochemistry With dilute sulphuric acid, water is oxidised at the anode in preference to sulphate: 2H₂O → O₂ + 4H⁺ + 4e⁻, so oxygen is released. (With concentrated acid, S₂O₈²⁻ forms.)
100	Alcohols, Phenols and EthersPreparation and properties	Class 12: Alcohols, Phenols and Ethers	Single correctMedium
A medium single correct question on preparation and properties, from Alcohols, Phenols and Ethers. NCERT: Class 12: Alcohols, Phenols and Ethers A Grignard reagent adds to a ketone to give a tertiary alcohol: (CH₃)₂C=O + CH₃MgCl, then hydrolysis, gives (CH₃)₃C–OH, tert-butyl alcohol.
101	p-Block ElementsGroup 16 elements	No matching NCERT chapter	Single correctMedium
A medium single correct question on group 16 elements, from p-Block Elements. NCERT: No matching NCERT chapter Peroxodisulphuric acid, HO₃S–O–O–SO₃H, has a peroxide link between its two sulphur atoms. Pyrosulphuric acid has an S–O–S bridge instead.
102	AminesClassification and identification of amines	Class 12: Amines	Single correctMedium
A medium single correct question on classification and identification of amines, from Amines. NCERT: Class 12: Amines Only primary amines give the carbylamine (isocyanide) test, on warming with chloroform and alcoholic KOH. Aniline, C₆H₅NH₂, is primary; the others are secondary or tertiary.
103	d- and f-Block ElementsTransition element properties	Class 12: The d- and f-Block Elements	Single correctMedium
A medium single correct question on transition element properties, from d- and f-Block Elements. NCERT: Class 12: The d- and f-Block Elements Cr²⁺ is 3d⁴, with four unpaired electrons, so μ = √(n(n + 2)) = √24 ≈ 4.90 BM.
104	ThermodynamicsFirst law and state functions	Class 11: Thermodynamics	Single correctMedium
A medium single correct question on first law and state functions, from Thermodynamics. NCERT: Class 11: Thermodynamics Adiabatic means q = 0; expansion into a vacuum means no work is done, w = 0. So ΔU = 0, and for an ideal gas the temperature does not change: ΔT = 0.
105	SolutionsColligative properties	Class 12: Solutions	Single correctMedium
A medium single correct question on colligative properties, from Solutions. NCERT: Class 12: Solutions ΔT_f = K_f × m = 5.12 × 0.078 = 0.399 K, which rounds to 0.40 K.
106	ElectrochemistryElectrochemical cells	Class 12: Electrochemistry	Single correctMedium
A medium single correct question on electrochemical cells, from Electrochemistry. NCERT: Class 12: Electrochemistry Ca²⁺ + 2e⁻ → Ca, so 2 F deposit one mole (40 g). 20 g is half a mole and needs 1 F.
107	Aldehydes, Ketones and Carboxylic AcidsAldol and Cannizzaro	Class 12: Aldehydes, Ketones and Carboxylic Acids	Single correctMedium
A medium single correct question on aldol and cannizzaro, from Aldehydes, Ketones and Carboxylic Acids. NCERT: Class 12: Aldehydes, Ketones and Carboxylic Acids Two different carbonyl compounds condensing in dilute alkali is a cross aldol condensation; with an aromatic aldehyde and a ketone it is also called the Claisen–Schmidt reaction.
108	Organic Chemistry: Some Basic Principles and TechniquesPurification methods	Class 11: Organic Chemistry – Some Basic Principles and Techniques	Single correctMedium
A medium single correct question on purification methods, from Organic Chemistry: Some Basic Principles and Techniques. NCERT: Class 11: Organic Chemistry – Some Basic Principles and Techniques In paper chromatography, water held in the paper is the stationary phase and the components partition between it and the moving solvent, so it is partition chromatography.
109	Chemical KineticsArrhenius equation	Class 12: Chemical Kinetics	Single correctMedium
A medium single correct question on arrhenius equation, from Chemical Kinetics. NCERT: Class 12: Chemical Kinetics More molecules per unit volume collide more often, so the collision frequency rises. Activation energy, threshold energy and heat of reaction do not depend on concentration.
110	States of MatterGas laws	No matching NCERT chapter	Single correctMedium
A medium single correct question on gas laws, from States of Matter. NCERT: No matching NCERT chapter n(N₂) = 7/28 = 0.25 mol and n(Ar) = 8/40 = 0.2 mol, so the mole fraction of N₂ is 0.25/0.45 = 5/9. By Dalton’s law, p(N₂) = 5/9 × 27 bar = 15 bar.
111	Isolation of MetalsSmelting and refining	No matching NCERT chapter	Single correctMedium
A medium single correct question on smelting and refining, from Isolation of Metals. NCERT: No matching NCERT chapter Pig iron from the blast furnace, with about 4% carbon, can be moulded into a variety of shapes. Wrought iron is the purest commercial iron; blister copper blisters from escaping SO₂; nickel is refined by the Mond process, and Van Arkel is used for zirconium and titanium.
112	Organic Chemistry: Some Basic Principles and TechniquesElectronic effects	Class 11: Organic Chemistry – Some Basic Principles and Techniques	Single correctMedium
A medium single correct question on electronic effects, from Organic Chemistry: Some Basic Principles and Techniques. NCERT: Class 11: Organic Chemistry – Some Basic Principles and Techniques The tert-butyl cation has nine α-C–H bonds that can hyperconjugate with the empty p orbital; the sec-butyl cation has five. More hyperconjugation spreads the charge more and stabilises the ion. Methyl groups are +I, not –I.
113	Chemistry in Everyday LifeCleansing agents	No matching NCERT chapter	Single correctMedium
A medium single correct question on cleansing agents, from Chemistry in Everyday Life. NCERT: No matching NCERT chapter Cetyltrimethylammonium bromide is a quaternary ammonium salt whose long chain carries the positive charge: a cationic detergent. Sodium lauryl sulphate and sodium dodecylbenzenesulphonate are anionic detergents, and sodium stearate is a soap.
114	Haloalkanes and HaloarenesElimination reactions	Class 12: Haloalkanes and Haloarenes	StatementsMedium
A medium statements question on elimination reactions, from Haloalkanes and Haloarenes. NCERT: Class 12: Haloalkanes and Haloarenes HBr is lost from the α-carbon and a β-carbon (β-elimination, dehydrohalogenation), and the more substituted alkene, pent-2-ene, is the main product, as Zaitsev’s rule predicts. No water is lost, so it is not dehydration.
115	SolutionsRaoult's law	Class 12: Solutions	Single correctMedium
A medium single correct question on raoult's law, from Solutions. NCERT: Class 12: Solutions Acetone breaks some of the hydrogen bonds between ethanol molecules, weakening the attractions, so the mixture shows positive deviation. Acetone and chloroform deviate negatively; the other two pairs are nearly ideal.
116	Coordination CompoundsCrystal field theory	Class 12: Coordination Compounds	Single correctMedium
A medium single correct question on crystal field theory, from Coordination Compounds. NCERT: Class 12: Coordination Compounds In the spectrochemical series, SCN⁻ < F⁻ < OH⁻ < C₂O₄²⁻ < H₂O < NCS⁻ < NH₃ < en < CN⁻ < CO, so the order is SCN⁻ < F⁻ < C₂O₄²⁻ < CN⁻.
117	BiomoleculesProteins	Class 12: Biomolecules	Single correctMedium
A medium single correct question on proteins, from Biomolecules. NCERT: Class 12: Biomolecules Lysine has a second amino group in its side chain, which makes it basic. Serine, alanine and tyrosine are neutral amino acids.
118	EquilibriumSolubility product	Class 11: Equilibrium	Single correctMedium
A medium single correct question on solubility product, from Equilibrium. NCERT: Class 11: Equilibrium HCl raises the chloride ion concentration, so the ionic product of NaCl exceeds its solubility product and pure NaCl crystallises (the common ion effect). MgCl₂ and CaCl₂ are far more soluble and stay in solution.
119	PolymersNatural rubber and cellulose	No matching NCERT chapter	Single correctMedium
A medium single correct question on natural rubber and cellulose, from Polymers. NCERT: No matching NCERT chapter Natural rubber is cis-1,4-polyisoprene. Buna-S (butadiene–styrene), polybutadiene and Buna-N (butadiene–acrylonitrile) are synthetic rubbers.
120	Environmental ChemistryAir and water pollution	No matching NCERT chapter	Single correctMedium
A medium single correct question on air and water pollution, from Environmental Chemistry. NCERT: No matching NCERT chapter Carboxyhaemoglobin is about 300 times more stable than oxyhaemoglobin, which is why CO is so harmful: it blocks haemoglobin from carrying oxygen. The other three statements are true.
121	BiomoleculesCarbohydrates	Class 12: Biomolecules	Single correctMedium
A medium single correct question on carbohydrates, from Biomolecules. NCERT: Class 12: Biomolecules Sucrose is made of α-D-glucose and β-D-fructose joined by a glycosidic link between C1 of glucose and C2 of fructose; hydrolysis releases these two.
122	s-Block ElementsBiological importance of sodium, potassium, magnesium and calcium	No matching NCERT chapter	Single correctMedium
A medium single correct question on biological importance of sodium, potassium, magnesium and calcium, from s-Block Elements. NCERT: No matching NCERT chapter Potassium ions activate many enzymes, take part in the oxidation of glucose to ATP, and together with sodium carry nerve signals.
123	Some Basic Concepts of ChemistryMole concept	Class 11: Some Basic Concepts of Chemistry	Single correctMedium
A medium single correct question on mole concept, from Some Basic Concepts of Chemistry. NCERT: Class 11: Some Basic Concepts of Chemistry Moles of atoms: Ag 1/108, Mg 1/24, O 2 × 1/32 = 1/16, Li 1/7. Lithium has the most, so 1 g of Li has the most atoms.
124	Structure of AtomElectronic configuration	Class 11: Structure of Atom	Single correctMedium
A medium single correct question on electronic configuration, from Structure of Atom. NCERT: Class 11: Structure of Atom The atomic number, 71, gives the protons and (in the neutral atom) the electrons; neutrons = 175 − 71 = 104.
125	Redox ReactionsOxidation number	Class 11: Redox Reactions	Single correctMedium
A medium single correct question on oxidation number, from Redox Reactions. NCERT: Class 11: Redox Reactions In CH₄, carbon is −4 (each H is +1); in CCl₄ it is +4 (each Cl is −1). So carbon goes from −4 to +4.
126	d- and f-Block ElementsTransition element properties	Class 12: The d- and f-Block Elements	Single correctMedium
A medium single correct question on transition element properties, from d- and f-Block Elements. NCERT: Class 12: The d- and f-Block Elements Chromium is +6 in both chromate and dichromate, so (4) is incorrect. Cr²⁺ is the stronger reductant because it goes to the stable d³ (half-filled t₂g) Cr³⁺, and statements (2) and (3) are true.
127	ThermodynamicsEntropy and Gibbs energy	Class 11: Thermodynamics	Single correctMedium
A medium single correct question on entropy and gibbs energy, from Thermodynamics. NCERT: Class 11: Thermodynamics Forming a bond releases energy, so ΔrH < 0, and two gas particles becoming one lowers the disorder, so ΔrS < 0.
128	Surface ChemistryColloids and their preparation	No matching NCERT chapter	Single correctMedium
A medium single correct question on colloids and their preparation, from Surface Chemistry. NCERT: No matching NCERT chapter The zeta (electrokinetic) potential is the potential difference across the double layer around a colloidal particle; the charge it reflects keeps particles apart, so it measures the stability of the colloid.
129	p-Block ElementsGroup 15 elements	No matching NCERT chapter	Single correctMedium
A medium single correct question on group 15 elements, from p-Block Elements. NCERT: No matching NCERT chapter Urea hydrolyses to ammonium carbamate (A), which decomposes to ammonia (B). Ammonia with Cu²⁺ gives the deep blue complex [Cu(NH₃)₄]²⁺ (C).
130	HydrogenHydrogen and its compounds	No matching NCERT chapter	MatchingMedium
A medium matching question on hydrogen and its compounds, from Hydrogen. NCERT: No matching NCERT chapter A mixture of CO and H₂ is synthesis gas; temporary hardness comes from the hydrogen carbonates of magnesium and calcium; B₂H₆ is an electron-deficient hydride; H₂O₂ has a non-planar (open book) structure: (a)-(iii), (b)-(i), (c)-(ii), (d)-(iv).
131	Classification of Elements and PeriodicityPeriodic trends	Class 11: Classification of Elements and Periodicity in Properties	MatchingMedium
A medium matching question on periodic trends, from Classification of Elements and Periodicity. NCERT: Class 11: Classification of Elements and Periodicity in Properties CO is a neutral oxide, BaO (a metal oxide) is basic, Al₂O₃ is amphoteric, and Cl₂O₇ (a non-metal oxide) is acidic: (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii).
132	Chemical KineticsIntegrated rate laws and half-life	Class 12: Chemical Kinetics	Single correctMedium
A medium single correct question on integrated rate laws and half-life, from Chemical Kinetics. NCERT: Class 12: Chemical Kinetics t = (2.303/k) log([R]₀/[R]) = (2.303 / 4.606 × 10⁻³) × log(2.0/0.2) = 500 × 1 = 500 s.
133	HydrocarbonsAlkenes and alkynes	Class 11: Hydrocarbons	Single correctMedium
A medium single correct question on alkenes and alkynes, from Hydrocarbons. NCERT: Class 11: Hydrocarbons Methanal comes only from a terminal =CH₂ group. Only allylcyclohexane, C₆H₁₁–CH₂–CH=CH₂, has one, and ozonolysis gives cyclohexylethanal and methanal. The others give ethanal or a ring-opened dialdehyde.
134	HydrocarbonsAlkanes	Class 11: Hydrocarbons	Single correctMedium
A medium single correct question on alkanes, from Hydrocarbons. NCERT: Class 11: Hydrocarbons The Wurtz reaction joins two alkyl groups and works well for symmetrical alkanes. n-Heptane (C₃ + C₄) needs two different alkyl halides, which give a mixture of hexane, heptane and octane that is hard to separate.
135	Alcohols, Phenols and EthersPreparation and properties	Class 12: Alcohols, Phenols and Ethers	Single correctMedium
A medium single correct question on preparation and properties, from Alcohols, Phenols and Ethers. NCERT: Class 12: Alcohols, Phenols and Ethers In an alkyl aryl ether, the O–aryl bond has partial double-bond character and is not broken; iodide attacks the methyl group. Anisole, C₆H₅OCH₃, gives phenol and methyl iodide.

Physics questions, each with its chapter and our explanation
Q	Chapter and topic	NCERT	Kind and level
136	Atoms and NucleiBohr model	Class 12: Atoms; Class 12: Nuclei	Single correctMedium
A medium single correct question on bohr model, from Atoms and Nuclei. NCERT: Class 12: Atoms; Class 12: Nuclei The Bohr model holds only for one-electron (hydrogen-like) systems. H, He⁺ and deuterium each have one electron; Ne⁺ has nine.
137	Electromagnetic WavesProperties of electromagnetic waves	Class 12: Electromagnetic Waves	Single correctMedium
A medium single correct question on properties of electromagnetic waves, from Electromagnetic Waves. NCERT: Class 12: Electromagnetic Waves The electric energy density ½ε₀E² equals the magnetic energy density B²/2μ₀, because E = cB and c² = 1/μ₀ε₀. The two fields contribute equally: 1 : 1.
138	OpticsPolarisation	Class 12: Ray Optics and Optical Instruments; Class 12: Wave Optics	Single correctMedium
A medium single correct question on polarisation, from Optics. NCERT: Class 12: Ray Optics and Optical Instruments; Class 12: Wave Optics tan i_b = μ, and light passes into a denser medium, so μ > 1. Then tan i_b > 1, which puts i_b between 45° and 90°.
139	Behaviour of Perfect Gas and Kinetic TheoryIdeal gas equation	Class 11: Kinetic Theory	Single correctMedium
A medium single correct question on ideal gas equation, from Behaviour of Perfect Gas and Kinetic Theory. NCERT: Class 11: Kinetic Theory ρ = PM/RT = (249 × 10³ Pa × 2 × 10⁻³ kg mol⁻¹) / (8.3 × 300) = 498 / 2490 = 0.2 kg m⁻³.
140	OpticsTotal internal reflection and prisms	Class 12: Ray Optics and Optical Instruments; Class 12: Wave Optics	Single correctMedium
A medium single correct question on total internal reflection and prisms, from Optics. NCERT: Class 12: Ray Optics and Optical Instruments; Class 12: Wave Optics The ray leaves normally, so r₂ = 0 and r₁ = A − r₂ = A. For small angles, i ≈ μr₁ = μA.
141	ThermodynamicsThermodynamic processes	Class 11: Thermodynamics	Single correctMedium
A medium single correct question on thermodynamic processes, from Thermodynamics. NCERT: Class 11: Thermodynamics The system is thermally insulated, so no heat enters or leaves: the free expansion is adiabatic. (For an ideal gas the temperature also ends unchanged, but the process is not a quasi-static isothermal one.)
142	Atoms and NucleiNuclear binding energy	Class 12: Atoms; Class 12: Nuclei	Single correctMedium
A medium single correct question on nuclear binding energy, from Atoms and Nuclei. NCERT: Class 12: Atoms; Class 12: Nuclei E = mc² = 0.5 × 10⁻³ kg × (3 × 10⁸ m s⁻¹)² = 0.5 × 10⁻³ × 9 × 10¹⁶ = 4.5 × 10¹³ J.
143	GravitationAcceleration due to gravity	Class 11: Gravitation	Single correctMedium
A medium single correct question on acceleration due to gravity, from Gravitation. NCERT: Class 11: Gravitation Gravitational force falls as 1/r². At h = R/2, r = 3R/2, so the force is 72 × (R / (3R/2))² = 72 × 4/9 = 32 N.
144	Electronic DevicesSemiconductors	Class 12: Semiconductor Electronics: Materials, Devices and Simple Circuits	Single correctMedium
A medium single correct question on semiconductors, from Electronic Devices. NCERT: Class 12: Semiconductor Electronics: Materials, Devices and Simple Circuits In insulators and semiconductors, heating frees more charge carriers, so resistance falls as temperature rises: a negative temperature coefficient. Metals have a positive one.
145	Oscillations and WavesSHM	Class 11: Oscillations; Class 11: Waves	Single correctMedium
A medium single correct question on shm, from Oscillations and Waves. NCERT: Class 11: Oscillations; Class 11: Waves In SHM, a = −ω²x, so acceleration is always opposite to displacement: they differ in phase by π radians.
146	Experimental SkillsVernier calipers and screw gauge	No matching NCERT chapter	Single correctMedium
A medium single correct question on vernier calipers and screw gauge, from Experimental Skills. NCERT: No matching NCERT chapter Least count = pitch / number of circular divisions, so pitch = 0.01 mm × 50 = 0.5 mm.
147	Oscillations and WavesStanding waves and beats	Class 11: Oscillations; Class 11: Waves	Single correctMedium
A medium single correct question on standing waves and beats, from Oscillations and Waves. NCERT: Class 11: Oscillations; Class 11: Waves B was 530 ± 6 Hz: 524 or 536 Hz. Lowering the tension lowers B’s frequency. From 536 Hz that would bring it closer to 530 and reduce the beats; from 524 Hz it moves away and the beats rise to 7 Hz. So B was 524 Hz.
148	Motion of System of Particles and Rigid BodyCentre of mass	Class 11: Systems of Particles and Rotational Motion	Single correctMedium
A medium single correct question on centre of mass, from Motion of System of Particles and Rigid Body. NCERT: Class 11: Systems of Particles and Rotational Motion Measured from the 5 kg particle, x = (5 × 0 + 10 × 1 m) / 15 = 2/3 m ≈ 67 cm.
149	Motion of System of Particles and Rigid BodyTorque and rotational dynamics	Class 11: Systems of Particles and Rotational Motion	Single correctMedium
A medium single correct question on torque and rotational dynamics, from Motion of System of Particles and Rigid Body. NCERT: Class 11: Systems of Particles and Rotational Motion τ = r × F = 2k̂ × 3ĵ = 6 (k̂ × ĵ) = −6î N m, since k̂ × ĵ = −î.
150	Electromagnetic WavesProperties of electromagnetic waves	Class 12: Electromagnetic Waves	Single correctMedium
A medium single correct question on properties of electromagnetic waves, from Electromagnetic Waves. NCERT: Class 12: Electromagnetic Waves Power = flux × area = 20 W cm⁻² × 20 cm² = 400 W. In 60 s the energy is 400 × 60 = 24 × 10³ J.
151	ElectrostaticsGauss's law	Class 12: Electric Charges and Fields; Class 12: Electrostatic Potential and Capacitance	Single correctMedium
A medium single correct question on gauss's law, from Electrostatics. NCERT: Class 12: Electric Charges and Fields; Class 12: Electrostatic Potential and Capacitance Outside the sphere the charge acts as a point charge at the centre: E = kq/r² = 9 × 10⁹ × 3.2 × 10⁻⁷ / (0.15)² = 2880 / 0.0225 = 1.28 × 10⁵ N C⁻¹.
152	ElectrostaticsElectric field and potential	Class 12: Electric Charges and Fields; Class 12: Electrostatic Potential and Capacitance	Single correctMedium
A medium single correct question on electric field and potential, from Electrostatics. NCERT: Class 12: Electric Charges and Fields; Class 12: Electrostatic Potential and Capacitance E = −dV/dr. A potential that is the same everywhere has no gradient, so the electric field is zero.
153	Electronic Devicesp-n junction diode	Class 12: Semiconductor Electronics: Materials, Devices and Simple Circuits	Single correctMedium
A medium single correct question on p-n junction diode, from Electronic Devices. NCERT: Class 12: Semiconductor Electronics: Materials, Devices and Simple Circuits Reverse bias pulls the majority carriers away from the junction and widens the depletion region; forward bias narrows it.
154	Electromagnetic Induction and Alternating CurrentsAC circuits	Class 12: Electromagnetic Induction; Class 12: Alternating Current	Single correctMedium
A medium single correct question on ac circuits, from Electromagnetic Induction and Alternating Currents. NCERT: Class 12: Electromagnetic Induction; Class 12: Alternating Current X_C = 1/(2πfC) = 1/(2π × 50 × 40 × 10⁻⁶) ≈ 79.6 Ω, so I_rms = V_rms/X_C = 200/79.6 ≈ 2.5 A.
155	Behaviour of Perfect Gas and Kinetic TheoryMean free path	Class 11: Kinetic Theory	Single correctMedium
A medium single correct question on mean free path, from Behaviour of Perfect Gas and Kinetic Theory. NCERT: Class 11: Kinetic Theory A molecule sweeps out collisions over a cross-section πd², and allowing for the motion of the others brings in √2: λ = 1/(√2 nπd²).
156	Electronic DevicesTransistors and logic gates	Class 12: Semiconductor Electronics: Materials, Devices and Simple Circuits	Single correctMedium
A medium single correct question on transistors and logic gates, from Electronic Devices. NCERT: Class 12: Semiconductor Electronics: Materials, Devices and Simple Circuits For transistor action the base must be very thin and lightly doped, so most carriers from the emitter cross it to the collector. The emitter is heavily doped and the collector largest; the emitter junction is forward biased and the collector junction reverse biased.
157	Dual Nature of Matter and RadiationPhotoelectric effect	Class 12: Dual Nature of Radiation and Matter	Single correctMedium
A medium single correct question on photoelectric effect, from Dual Nature of Matter and Radiation. NCERT: Class 12: Dual Nature of Radiation and Matter Halving 1.5 ν₀ gives 0.75 ν₀, below the threshold frequency. No photoelectrons are emitted however intense the light, so the current is zero.
158	Atoms and NucleiNuclear fission and fusion	Class 12: Atoms; Class 12: Nuclei	Single correctMedium
A medium single correct question on nuclear fission and fusion, from Atoms and Nuclei. NCERT: Class 12: Atoms; Class 12: Nuclei Balance mass and charge: 235 + 1 = 89 + 3 + A gives A = 144, and 92 = 36 + Z gives Z = 56, which is barium: ¹⁴⁴₅₆Ba.
159	Physical World and MeasurementUnits and dimensions	Class 11: Units and Measurement	Single correctMedium
A medium single correct question on units and dimensions, from Physical World and Measurement. NCERT: Class 11: Units and Measurement 1 eV = 1.6 × 10⁻¹⁹ J, so 10⁻²⁰ J = 10⁻²⁰ / 1.6 × 10⁻¹⁹ ≈ 0.0625 eV, nearly 0.06 eV.
160	Laws of MotionNewton's laws	Class 11: Laws of Motion	Single correctMedium
A medium single correct question on newton's laws, from Laws of Motion. NCERT: Class 11: Laws of Motion The heavier body falls and the lighter rises with the same acceleration. The net pulling force is (m₂ − m₁)g on a total mass m₁ + m₂, so a = (6 − 4)g / 10 = g/5.
161	Properties of Bulk MatterElasticity	Class 11: Mechanical Properties of Solids; Class 11: Mechanical Properties of Fluids; Class 11: Thermal Properties of Matter	Single correctMedium
A medium single correct question on elasticity, from Properties of Bulk Matter. NCERT: Class 11: Mechanical Properties of Solids; Class 11: Mechanical Properties of Fluids; Class 11: Thermal Properties of Matter Y = stress/strain = (Mg/A) / ((L₁ − L)/L) = MgL / (A(L₁ − L)).
162	Behaviour of Perfect Gas and Kinetic TheoryDegrees of freedom	Class 11: Kinetic Theory	Single correctMedium
A medium single correct question on degrees of freedom, from Behaviour of Perfect Gas and Kinetic Theory. NCERT: Class 11: Kinetic Theory A monatomic molecule has three translational degrees of freedom, each with ½k_BT, so its average energy is (3/2)k_BT.
163	Current ElectricityResistivity	Class 12: Current Electricity	Single correctMedium
A medium single correct question on resistivity, from Current Electricity. NCERT: Class 12: Current Electricity The resistivity of a metal rises with temperature. ρ_T = ρ₀[1 + α(T − T₀)] holds only over a limited range; over a wide range, as NCERT’s graph for copper shows, ρ starts at a small non-zero value and rises ever more steeply.
164	Current ElectricityResistivity	Class 12: Current Electricity	Single correctMedium
A medium single correct question on resistivity, from Current Electricity. NCERT: Class 12: Current Electricity Yellow = 4, violet = 7, brown = multiplier 10¹, gold = ±5%. So R = 47 × 10 = 470 Ω with 5% tolerance.
165	OpticsInterference and diffraction	Class 12: Ray Optics and Optical Instruments; Class 12: Wave Optics	Single correctMedium
A medium single correct question on interference and diffraction, from Optics. NCERT: Class 12: Ray Optics and Optical Instruments; Class 12: Wave Optics β = λD/d. Doubling D and halving d multiplies β by 2 × 2 = 4.
166	ElectrostaticsConductors and dielectrics	Class 12: Electric Charges and Fields; Class 12: Electrostatic Potential and Capacitance	Single correctMedium
A medium single correct question on conductors and dielectrics, from Electrostatics. NCERT: Class 12: Electric Charges and Fields; Class 12: Electrostatic Potential and Capacitance K = 30/6 = 5, so ε = Kε₀ = 5 × 8.85 × 10⁻¹² = 4.425 × 10⁻¹¹ ≈ 0.44 × 10⁻¹⁰ C² N⁻¹ m⁻².
167	Physical World and MeasurementDimensional analysis	Class 11: Units and Measurement	Single correctMedium
A medium single correct question on dimensional analysis, from Physical World and Measurement. NCERT: Class 11: Units and Measurement Stress is force per unit area, so its dimensions are [MLT⁻²]/[L²] = [ML⁻¹T⁻²], the same as pressure.
168	OpticsOptical instruments	Class 12: Ray Optics and Optical Instruments; Class 12: Wave Optics	Single correctMedium
A medium single correct question on optical instruments, from Optics. NCERT: Class 12: Ray Optics and Optical Instruments; Class 12: Wave Optics The limit of resolution of a telescope objective is Δθ = 1.22λ/D = 1.22 × 600 × 10⁻⁹ m / 2 m = 3.66 × 10⁻⁷ rad.
169	Electromagnetic Induction and Alternating CurrentsLCR circuits and resonance	Class 12: Electromagnetic Induction; Class 12: Alternating Current	Single correctMedium
A medium single correct question on lcr circuits and resonance, from Electromagnetic Induction and Alternating Currents. NCERT: Class 12: Electromagnetic Induction; Class 12: Alternating Current The two cases give tan(π/3) = X_C/R and tan(π/3) = X_L/R, so X_L = X_C. The full circuit is at resonance, the current is in phase with the voltage, and the power factor cos φ = 1.
170	ElectrostaticsElectric dipole	Class 12: Electric Charges and Fields; Class 12: Electrostatic Potential and Capacitance	Single correctMedium
A medium single correct question on electric dipole, from Electrostatics. NCERT: Class 12: Electric Charges and Fields; Class 12: Electrostatic Potential and Capacitance V = kp cos θ / r² = 9 × 10⁹ × 16 × 10⁻⁹ × 0.5 / (0.6)² = 72 / 0.36 = 200 V.
171	Magnetic Effects of Current and MagnetismMagnetic properties of materials	Class 12: Moving Charges and Magnetism; Class 12: Magnetism and Matter	Single correctMedium
A medium single correct question on magnetic properties of materials, from Magnetic Effects of Current and Magnetism. NCERT: Class 12: Moving Charges and Magnetism; Class 12: Magnetism and Matter μ = μ₀(1 + χ) = 4π × 10⁻⁷ × 600 = 2.4π × 10⁻⁴ T m A⁻¹. The magnetising field is not needed.
172	Magnetic Effects of Current and MagnetismAmpere's law	Class 12: Moving Charges and Magnetism; Class 12: Magnetism and Matter	Single correctMedium
A medium single correct question on ampere's law, from Magnetic Effects of Current and Magnetism. NCERT: Class 12: Moving Charges and Magnetism; Class 12: Magnetism and Matter n = 100/0.5 m = 200 turns per metre, so B = μ₀nI = 4π × 10⁻⁷ × 200 × 2.5 = 2π × 10⁻⁴ ≈ 6.28 × 10⁻⁴ T.
173	Current ElectricityDrift velocity and mobility	Class 12: Current Electricity	Single correctMedium
A medium single correct question on drift velocity and mobility, from Current Electricity. NCERT: Class 12: Current Electricity Mobility μ = v_d/E = 7.5 × 10⁻⁴ / 3 × 10⁻¹⁰ = 2.5 × 10⁶ m² V⁻¹ s⁻¹.
174	Properties of Bulk MatterThermal expansion and calorimetry	Class 11: Mechanical Properties of Solids; Class 11: Mechanical Properties of Fluids; Class 11: Thermal Properties of Matter	Single correctMedium
A medium single correct question on thermal expansion and calorimetry, from Properties of Bulk Matter. NCERT: Class 11: Mechanical Properties of Solids; Class 11: Mechanical Properties of Fluids; Class 11: Thermal Properties of Matter Q = mcΔT, and for the same material the mass goes as r³. So Q₁/Q₂ = (r₁/r₂)³ = (1.5)³ = 27/8.
175	Dual Nature of Matter and Radiationde Broglie wavelength	Class 12: Dual Nature of Radiation and Matter	Single correctMedium
A medium single correct question on de broglie wavelength, from Dual Nature of Matter and Radiation. NCERT: Class 12: Dual Nature of Radiation and Matter For an electron, λ = 1.227/√V nm. So √V = 1.227 / 1.227 × 10⁻² = 100, and V = 10⁴ V.
176	Physical World and MeasurementSignificant figures	Class 11: Units and Measurement	Single correctMedium
A medium single correct question on significant figures, from Physical World and Measurement. NCERT: Class 11: Units and Measurement In subtraction the result keeps as many decimal places as the least precise number: two, from 9.99. 9.99 − 0.0099 = 9.9801, which rounds to 9.98 m.
177	KinematicsMotion in a straight line	Class 11: Motion in a Straight Line; Class 11: Motion in a Plane	Single correctMedium
A medium single correct question on motion in a straight line, from Kinematics. NCERT: Class 11: Motion in a Straight Line; Class 11: Motion in a Plane v² = u² + 2gh, so 80² = 20² + 2 × 10 × h, giving 6400 − 400 = 20h and h = 300 m.
178	Properties of Bulk MatterSurface tension	Class 11: Mechanical Properties of Solids; Class 11: Mechanical Properties of Fluids; Class 11: Thermal Properties of Matter	Single correctMedium
A medium single correct question on surface tension, from Properties of Bulk Matter. NCERT: Class 11: Mechanical Properties of Solids; Class 11: Mechanical Properties of Fluids; Class 11: Thermal Properties of Matter The rise h ∝ 1/r, so the mass πr²hρ ∝ r. Doubling the radius doubles the mass: 10.0 g. (Equivalently, the weight held up equals 2πrT cos θ.)
179	Current ElectricityMetre bridge	Class 12: Current Electricity	Single correctMedium
A medium single correct question on metre bridge, from Current Electricity. NCERT: Class 12: Current Electricity At balance X/10 = 3/2, so X = 15 Ω. The wire is 1.5 m long, so 1 Ω of it is 1.5/15 = 0.1 m = 1.0 × 10⁻¹ m.
180	Electronic DevicesLogic gates	Class 12: Semiconductor Electronics: Materials, Devices and Simple Circuits	Single correctMedium
A medium single correct question on logic gates, from Electronic Devices. NCERT: Class 12: Semiconductor Electronics: Materials, Devices and Simple Circuits Y = NOT(Ā + B̄) = A · B by De Morgan’s theorem, so the circuit is an AND gate: Y is 1 only when A = B = 1.

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