1
Chapter 1: Crop Production and Management
NCERT Exercise Questions 1 to 11 (Complete)
Q1
Fill in the blanks: (a) Crop (b) Preparation (c) Float (d) Water, Nutrients
1 Mark Each
✅ CBSE Standard Answer
(a) crop (b) preparation (c) float (d) water and nutrients
CBSE Marking Scheme
Each correct blank1 Mark each
Q2
Match items in Column A with Column B: (i) Kharif crops ➔ Paddy & maize, (ii) Rabi crops ➔ Wheat, gram, pea, (iii) Chemical fertilisers ➔ Urea & super phosphate, (iv) Organic manure ➔ Animal excreta, cow dung, plant waste.
1 Mark Each
✅ CBSE Standard Answer
(i) Kharif crops ➔ Paddy and maize; (ii) Rabi crops ➔ Wheat, gram, pea; (iii) Chemical fertilisers ➔ Urea and super phosphate; (iv) Organic manure ➔ Animal excreta, cow dung, urine and plant waste.
Q3
Give two examples of each: (a) Kharif crop (b) Rabi crop
2 Marks
✅ CBSE Standard Answer
(a) Kharif crops: Paddy (Rice) and Maize.
(b) Rabi crops: Wheat and Gram.
(b) Rabi crops: Wheat and Gram.
Q4
Write a paragraph on: (a) Preparation of soil (b) Sowing (c) Weeding (d) Threshing
4 Marks
✅ CBSE Standard Answer
(a) Soil Preparation: Loosening and turning soil using plough so roots penetrate deep and breathe. Promotes earthworms and friendly microbes adding humus.
(b) Sowing: Selection of clean, healthy seeds using water flotation test, then planting at proper depth using seed drills.
(c) Weeding: Removing wild competitive plants (weeds) manually with khurpi or spraying 2,4-D weedicides.
(d) Threshing: Separating harvested grain seeds from chaff/stalks using a thresher or combine harvester.
CBSE Marking Scheme
Each paragraph with technical terms1 Mark each
Q5
Explain how fertilisers are different from manure.
3 Marks
✅ CBSE Standard Answer
Fertilisers are factory-made inorganic chemical salts rich in specific N, P, K nutrients but add no humus. Manure is natural organic decomposed plant/animal waste providing rich humus and improving soil texture without causing water pollution.
Q6
What is irrigation? Describe two water-conserving irrigation methods.
3 Marks
✅ CBSE Standard Answer
Irrigation is artificial water supply to crops at regular intervals. Methods: (1) Drip System: Water drops directly at root zone via pipes (zero wastage). (2) Sprinkler System: Rotating nozzles spray water like rain (best for uneven land).
Q7
If wheat is sown in Kharif season, what would happen?
2 Marks
✅ CBSE Standard Answer
Wheat requires cold dry winter weather. In Kharif (monsoon), excess rain causes waterlogging, seed rot, and severe fungal pest attacks, destroying crop yield.
Q8
Explain how soil is affected by continuous crop plantation.
2 Marks
✅ CBSE Standard Answer
Depletes soil nutrients (N, P, K), rendering soil infertile. Restored by crop rotation with leguminous plants or applying manure.
Q9
What are weeds? How can we control them?
3 Marks
✅ CBSE Standard Answer
Undesirable wild plants in field. Controlled by tilling before sowing, manual uprooting (khurpi), or spraying weedicides (2,4-D).
Q10
Arrange in proper order: (1) Sugar factory (2) Irrigation (3) Harvesting (4) Sowing (5) Preparation of soil (6) Ploughing (7) Manuring
2 Marks
✅ CBSE Standard Answer
5 (Preparation of soil) ➔ 6 (Ploughing) ➔ 4 (Sowing) ➔ 7 (Manuring) ➔ 2 (Irrigation) ➔ 3 (Harvesting) ➔ 1 (Sugar factory)
Q11
Crossword puzzle: Down: 1. Irrigation 2. Storage 5. Crop. Across: 3. Harvester 4. Gram 6. Winnowing
3 Marks
✅ CBSE Standard Answer
Down: 1. IRRIGATION, 2. STORAGE, 5. CROP. Across: 3. HARVESTER, 4. GRAM, 6. WINNOWING.
2
Chapter 2: Microorganisms: Friend and Foe
NCERT Exercise Questions 1 to 9 (Complete)
Q1
Fill in blanks: (a) Microscope (b) Nitrogen (c) Yeast (d) Bacteria
1 Mark Each
✅ CBSE Standard Answer
(a) microscope (b) nitrogen (c) yeast (d) bacteria (Vibrio cholerae)
Q2
Tick correct answer: (a) Yeast in production of: (ii) alcohol (b) Antibiotic is: (ii) Streptomycin (c) Carrier of malaria protozoan: (i) female Anopheles (d) Common carrier: (ii) housefly (e) Bread dough rises: (iii) growth of yeast cells (f) Sugar to alcohol: (iii) fermentation
1 Mark Each
✅ CBSE Standard Answer
(a) (ii) alcohol (b) (ii) Streptomycin (c) (i) female Anopheles (d) (ii) housefly (e) (iii) growth of yeast cells (f) (iii) fermentation
Q3
Match Column A & B: Bacteria ➔ Cholera, Rhizobium ➔ Nitrogen fixation, Lactobacillus ➔ Setting curd, Yeast ➔ Baking bread, Protozoan ➔ Malaria, Virus ➔ AIDS
1 Mark Each
✅ CBSE Standard Answer
(i) Bacteria ➔ Cholera (ii) Rhizobium ➔ Nitrogen fixation (iii) Lactobacillus ➔ Setting curd (iv) Yeast ➔ Baking bread (v) Protozoan ➔ Malaria (vi) Virus ➔ AIDS
Q4
Can microorganisms be seen with naked eye? How?
2 Marks
✅ CBSE Standard Answer
No. Observed under microscope or magnifying glass (bread mould).
Q5
What are major groups of microorganisms?
2 Marks
✅ CBSE Standard Answer
1. Bacteria 2. Fungi 3. Protozoa 4. Algae (and Viruses).
Q6
Name microorganisms which fix atmospheric nitrogen.
1 Mark
✅ CBSE Standard Answer
Rhizobium bacteria, Azotobacter, and Blue-green algae.
Q7
Write 10 lines on usefulness of microorganisms.
5 Marks
✅ CBSE Standard Answer
1. Curd setting (Lactobacillus) 2. Bread baking (Yeast) 3. Commercial alcohol fermentation 4. Antibiotic production 5. Vaccine preparation 6. Biological nitrogen fixation 7. Organic decomposition cleanup 8. Vinegar production 9. Sewage water treatment 10. Intestinal gut digestion.
Q8
Short paragraph on harmful effects of microorganisms.
3 Marks
✅ CBSE Standard Answer
Pathogens cause human diseases (TB, cholera, malaria, flu), animal anthrax, plant rusts, and spoil stored food releasing toxic toxins.
Q9
What are antibiotics? Precautions while taking them.
3 Marks
✅ CBSE Standard Answer
Medicines killing bacteria (Penicillin, Streptomycin). Precautions: Doctor's prescription, finish full course, avoid unnecessary usage, ineffective against viral cold/flu.
3
Chapter 3: Synthetic Fibres and Plastics
NCERT Exercise Questions 1 to 15 (Complete)
Q1
Explain why some fibres are called synthetic.
1 Mark
✅ CBSE Standard Answer
Synthesised chemically by humans using petrochemical polymers.
Q2
Rayon is different from synthetic fibres because: (b) it is obtained from wood pulp.
1 Mark
✅ CBSE Standard Answer
(b) Obtained from natural wood pulp chemically treated.
Q3
Fill in blanks: (a) artificial / man-made (b) petrochemicals (c) polymer.
1 Mark Each
✅ CBSE Standard Answer
(a) artificial/man-made (b) petrochemicals (c) polymer
Q4
Examples showing nylon is very strong.
2 Marks
✅ CBSE Standard Answer
Parachutes, rock climbing ropes, seat belts (stronger than steel wire).
Q5
Why plastic containers favoured for storing food.
2 Marks
✅ CBSE Standard Answer
Non-reactive with food, light weight, strong, cheap, durable.
Q6
Thermoplastic vs Thermosetting plastic.
3 Marks
✅ CBSE Standard Answer
Thermoplastics soften on heating & remolded (PVC, Polythene). Thermosetting set permanently & cannot be remolded (Bakelite, Melamine).
Q7
Why made of thermosetting: (a) Saucepan handles (b) Electric plugs/switches
2 Marks
✅ CBSE Standard Answer
Bakelite is poor conductor of heat (saucepan handle) and electricity (switches) and does not melt.
Q8
Recycled vs Non-recycled plastics list.
2 Marks
✅ CBSE Standard Answer
Recycled: Plastic toys, carry bags, bowls, wire cover. Non-recycled: Telephone, cooker handles, switches.
Q9
Cotton vs Synthetic shirt for Rana in summer.
2 Marks
✅ CBSE Standard Answer
Cotton shirt because it absorbs sweat and evaporates it to cool the body.
Q10
Examples showing plastics non-corrosive.
2 Marks
✅ CBSE Standard Answer
Storing acids/cleaners in plastic bottles; PVC water pipes.
Q11
Toothbrush handle & bristles same material?
2 Marks
✅ CBSE Standard Answer
No. Bristles soft/flexible (nylon), handle rigid/firm (hard plastic).
Q12
'Avoid plastics as far as possible' comment.
3 Marks
✅ CBSE Standard Answer
Plastics non-biodegradable, cause pollution and clog drains. Follow 5 R rule.
Q13
Match Polyester ➔ wrinkle free, Teflon ➔ non-stick cookware, Rayon ➔ wood pulp, Nylon ➔ parachutes.
1 Mark Each
✅ CBSE Standard Answer
Polyester: Wrinkle-free; Teflon: Non-stick; Rayon: Wood pulp; Nylon: Parachutes.
Q14
'Synthetic fibres help conservation of forests' comment.
2 Marks
✅ CBSE Standard Answer
Synthetic fibres made chemically from oil, saving trees used for rayon/wood pulp.
Q15
Activity showing thermoplastic poor conductor of electricity.
3 Marks
✅ CBSE Standard Answer
Insert plastic scale in cell-bulb circuit; bulb does not glow.
4
Chapter 4: Materials — Metals and Non-Metals
NCERT Exercise Questions 1 to 11 (Complete)
Q1
Which can be beaten into thin sheets? (a) Zinc (b) Phosphorus (c) Sulphur (d) Oxygen
1 Mark
✅ CBSE Standard Answer
(a) Zinc
Q2
Which statement is correct? (c) Generally, metals are ductile.
1 Mark
✅ CBSE Standard Answer
(c) Generally, metals are ductile
Q3
Fill in blanks: (a) reactive (b) good, electricity (c) more (d) hydrogen.
1 Mark Each
✅ CBSE Standard Answer
(a) reactive (b) good, electricity (c) more (d) hydrogen
Q4
Mark T/F: (a) F (b) T (c) F (d) F
1 Mark Each
✅ CBSE Standard Answer
(a) False (b) True (c) False (d) False
Q5
Distinguish metals and non-metals on properties.
3 Marks
✅ CBSE Standard Answer
Metals: Lustrous, hard, malleable, ductile, good heat & electricity conductors. Non-metals: Dull, soft/brittle, non-malleable, non-ductile, poor conductors.
Q6
Reasons: (a) Aluminium foil wrap food (b) Immersion rods metallic (c) Copper cannot displace zinc (d) Na & K stored in kerosene.
4 Marks
✅ CBSE Standard Answer
(a) Malleable & non-reactive. (b) Metals conduct heat & electricity. (c) Cu is less reactive than Zn. (d) Na & K react violently with air/water.
Q7
Can lemon pickle be stored in aluminium utensil? Explain.
2 Marks
✅ CBSE Standard Answer
No. Lemon contains acid which reacts with aluminium producing poisonous salts and hydrogen gas.
Q8
Match: Gold ➔ Jewellery, Iron ➔ Machinery, Aluminium ➔ Wrapping food, Carbon ➔ Fuel, Copper ➔ Electric wire, Mercury ➔ Thermometers.
2 Marks
✅ CBSE Standard Answer
Gold: Jewellery; Iron: Machinery; Aluminium: Wrapping food; Carbon: Fuel; Copper: Electric wire; Mercury: Thermometers.
Q9
What happens when: (a) Dilute H2SO4 on copper plate (b) Iron nails in copper sulphate solution + word equations.
3 Marks
✅ CBSE Standard Answer
(a) No reaction cold dil H2SO4; hot conc acid produces CuSO4 + SO2 + H2O. (b) Displacement: Iron + Copper sulphate ➔ Iron sulphate + Copper.
Q10
Saloni burning charcoal gas test & equations.
2 Marks
✅ CBSE Standard Answer
CO2 gas. Dissolve in water ➔ Carbonic acid turns blue litmus red. C + O2 ➔ CO2; CO2 + H2O ➔ H2CO3.
Q11
Gold jewellery polished weight loss explanation.
2 Marks
✅ CBSE Standard Answer
Aqua regia solution dissolves outer dull gold layer, exposing shiny inner layer with slight weight drop.
5
Chapter 5: Coal and Petroleum
NCERT Exercise Questions 1 to 9 (Complete)
Q1
Advantages of CNG and LPG as fuels.
2 Marks
✅ CBSE Standard Answer
Clean fuels, high heat output, low smoke pollution, easy pipe transport.
Q2
Petroleum product used for surfacing roads.
1 Mark
✅ CBSE Standard Answer
Bitumen
Q3
Describe how coal is formed from dead vegetation. Process name.
3 Marks
✅ CBSE Standard Answer
Forests buried 300M years ago under soil converted to coal under high temp & pressure in absence of air. Process: Carbonisation.
Q4
Fill in blanks: (a) Coal, Petroleum, Natural gas (b) Refining (c) CNG.
1 Mark Each
✅ CBSE Standard Answer
(a) Coal, Petroleum, Natural gas (b) Refining (c) CNG
Q5
Mark T/F: (a) F (b) F (c) T (d) F.
1 Mark Each
✅ CBSE Standard Answer
(a) False (b) False (c) True (d) False
Q6
Explain why fossil fuels are exhaustible natural resources.
2 Marks
✅ CBSE Standard Answer
Took millions of years to form and existing reserves are limited while consumption is extremely fast.
Q7
Describe characteristics and uses of coke.
3 Marks
✅ CBSE Standard Answer
Tough, porous, black substance, ~90% pure carbon. Used in steel manufacturing and metal extraction reducing agent.
Q8
Explain process of formation of petroleum.
3 Marks
✅ CBSE Standard Answer
Dead marine organisms buried under sand/clay millions of years ago converted to oil & gas under high pressure/temp in absence of air.
Q9
Power shortage graph analysis.
2 Marks
✅ CBSE Standard Answer
Data shows power deficit rising annually; underscores urgent need for PCRA fuel saving guidelines & solar/wind energy adoption.
6
Chapter 6: Combustion and Flame
NCERT Exercise Questions 1 to 13 (Complete)
Q1
List conditions under which combustion takes place.
2 Marks
✅ CBSE Standard Answer
1. Fuel 2. Air/Oxygen 3. Ignition temperature.
Q2
Fill in blanks: (a) pollution (b) LPG (c) ignition temperature (d) water.
1 Mark Each
✅ CBSE Standard Answer
(a) pollution (b) LPG (c) ignition temperature (d) water
Q3
CNG in automobiles reduced pollution. Explain.
2 Marks
✅ CBSE Standard Answer
CNG burns cleanly leaving no unburnt carbon soot or harmful sulphur/nitrogen oxides.
Q4
Compare LPG and wood as fuels.
3 Marks
✅ CBSE Standard Answer
LPG has higher calorific value (55,000 vs 17,000 kJ/kg), produces zero smoke/ash, and doesn't cause deforestation.
Q5
Give reasons: (a) Water not for electrical fires (b) LPG better fuel (c) Paper on aluminium pipe doesn't burn easily.
3 Marks
✅ CBSE Standard Answer
(a) Water conducts electricity risking electrocution. (b) LPG high heat, smoke-free. (c) Aluminium metal conducts heat away preventing paper reaching ignition temperature.
Q6
Labelled diagram of candle flame.
3 Marks
✅ CBSE Standard Answer
1. Outermost blue (complete, hottest) 2. Middle yellow (luminous, partial) 3. Innermost dark (unburnt wax).
Q7
Unit of calorific value.
1 Mark
✅ CBSE Standard Answer
kJ/kg (kilojoules per kilogram).
Q8
Explain how CO2 controls fire.
2 Marks
✅ CBSE Standard Answer
CO2 is heavier than O2, blankets fire cutting off air supply, and cools fuel temperature.
Q9
Difficult to burn green leaves vs dry leaves.
2 Marks
✅ CBSE Standard Answer
Green leaves contain moisture absorbing heat and raising ignition temp. Dry leaves have no water catching fire instantly.
Q10
Zone of flame goldsmith uses & why.
2 Marks
✅ CBSE Standard Answer
Outermost blue non-luminous zone (hottest part with complete combustion).
Q11
Numerical: 4.5 kg fuel burnt, 180,000 kJ heat. Calculate calorific value.
2 Marks
✅ CBSE Standard Answer
Calorific value = Heat / Mass = 180,000 / 4.5 = 40,000 kJ/kg.
Q12
Can rusting be called combustion? Discuss.
2 Marks
✅ CBSE Standard Answer
Yes, slow oxidation producing heat, but no light/flame produced.
Q13
Abida (outer zone) vs Ramesh (yellow inner zone) water heating.
2 Marks
✅ CBSE Standard Answer
Abida's water heats faster because outermost blue zone is hottest.
7
Chapter 7: Conservation of Plants and Animals
NCERT Exercise Questions 1 to 11 (Complete)
Q1
Fill in blanks: (a) Sanctuary (b) Endemic (c) Climatic.
1 Mark Each
✅ CBSE Standard Answer
(a) Sanctuary (b) Endemic (c) Climatic
Q2
Differentiate: (a) Sanctuary vs Biosphere Reserve (b) Zoo vs Sanctuary (c) Endangered vs Extinct (d) Flora vs Fauna.
4 Marks
✅ CBSE Standard Answer
(a) Sanctuary protects wild animals; Biosphere conserves total ecosystem & tribal culture. (b) Zoo is artificial human setup; Sanctuary is natural habitat. (c) Endangered facing extinction; Extinct no longer exist. (d) Flora = Plants; Fauna = Animals.
Q3
Deforestation effects on animals, environment, villages, cities, earth, next generation.
3 Marks
✅ CBSE Standard Answer
Destroys animal habitat, increases CO2 global warming, causes soil erosion & floods, lowers water table.
Q4
What happens if: (a) keep cutting trees (b) habitat disturbed (c) top soil exposed.
3 Marks
✅ CBSE Standard Answer
(a) Desertification & rain drop. (b) Species become endangered. (c) Desertification (humus loss).
Q5
Short answers: Biodiversity conservation, Red Data Book, Migration.
3 Marks
✅ CBSE Standard Answer
Biodiversity maintains ecosystem balance. Red Data Book lists endangered species. Migration is seasonal bird movement.
Q6
Is cutting trees for factory projects justified?
2 Marks
✅ CBSE Standard Answer
No. Environmental destruction must be compensated by mandatory reforestation.
Q7
How contribute to green wealth of locality?
2 Marks
✅ CBSE Standard Answer
Planting saplings, watering plants, community drives, protecting trees.
Q8
Deforestation leading to reduced rainfall.
2 Marks
✅ CBSE Standard Answer
Trees release moisture by transpiration. Fewer trees = less transpiration clouds & higher temp.
Q9
National parks in state.
1 Mark
✅ CBSE Standard Answer
Jim Corbett, Gir, Kaziranga, Ranthambore.
Q10
Why save paper & ways to save paper.
2 Marks
✅ CBSE Standard Answer
17 trees cut for 1 tonne paper. Ways: Recycle, write both sides, use digital.
Q11
Word puzzle on conservation.
2 Marks
✅ CBSE Standard Answer
ENDANGERED, DINOSAUR, RED DATA BOOK.
8
Chapter 8: Cell — Structure and Functions
NCERT Exercise Questions 1 to 10 (Complete)
Q1
True/False: (a) T (b) F (c) F (d) T
1 Mark Each
✅ CBSE Standard Answer
(a) True (b) False (c) False (d) True
Q2
Sketch human nerve cell & function.
3 Marks
✅ CBSE Standard Answer
Neuron receives & transmits electrical signals between brain and body parts.
Q3
Short notes: Cytoplasm & Nucleus.
3 Marks
✅ CBSE Standard Answer
Cytoplasm: Jelly-like fluid containing organelles. Nucleus: Spherical control center containing genes/chromosomes.
Q4
Part of cell containing organelles.
1 Mark
✅ CBSE Standard Answer
Cytoplasm
Q5
Plant vs Animal cell differences.
4 Marks
✅ CBSE Standard Answer
Plant cell has cell wall, chloroplasts, large vacuole. Animal cell lacks cell wall & chloroplasts, has small vacuoles.
Q6
Eukaryotes vs Prokaryotes.
2 Marks
✅ CBSE Standard Answer
Prokaryotes lack nuclear membrane (Bacteria). Eukaryotes have true nuclear membrane (Onion/Cheek cell).
Q7
Chromosomes location & function.
2 Marks
✅ CBSE Standard Answer
Found in nucleus. Carry genes transferring hereditary traits from parents to offspring.
Q8
'Cells basic structural units' explain.
2 Marks
✅ CBSE Standard Answer
Like bricks forming a building, cells form tissues ➔ organs ➔ organism.
Q9
Why chloroplasts in plant cells only.
2 Marks
✅ CBSE Standard Answer
Contain chlorophyll for photosynthesis (making food from sunlight).
Q10
Crossword puzzle.
2 Marks
✅ CBSE Standard Answer
NUCLEUS, PLASTID, CYTOPLASM, NERVE, CELL WALL.
9
Chapter 9: Reproduction in Animals
NCERT Exercise Questions 1 to 10 (Complete)
Q1
Importance of reproduction.
2 Marks
✅ CBSE Standard Answer
Ensures continuation of species preventing extinction.
Q2
Process of fertilisation in humans.
3 Marks
✅ CBSE Standard Answer
Sperm fuses with ovum in fallopian tube forming single-celled zygote (Internal fertilisation).
Q3
Choose correct answer: (a) inside female body (b) metamorphosis (c) ONE.
1 Mark Each
✅ CBSE Standard Answer
(a) inside female body (b) metamorphosis (c) one
Q4
True/False: (a) T (b) T (c) T (d) F (e) T (f) F.
1 Mark Each
✅ CBSE Standard Answer
(a) True (b) True (c) True (d) False (e) True (f) False
Q5
Differences between zygote and foetus.
2 Marks
✅ CBSE Standard Answer
Zygote is single-celled initial fertilised egg. Foetus is multicellular stage where body parts are identifiable.
Q6
Define asexual reproduction & 2 methods.
3 Marks
✅ CBSE Standard Answer
Reproduction by single parent. Methods: Binary Fission (Amoeba) and Budding (Hydra).
Q7
Female organ where embryo gets embedded.
1 Mark
✅ CBSE Standard Answer
Uterus
Q8
What is metamorphosis? Examples.
2 Marks
✅ CBSE Standard Answer
Drastic transformation of larva into adult. Examples: Frog (tadpole ➔ frog), Silk moth.
Q9
Internal vs External fertilisation.
2 Marks
✅ CBSE Standard Answer
Internal occurs inside female body (humans, cows). External occurs outside in water (frogs, fish).
Q10
Crossword puzzle.
2 Marks
✅ CBSE Standard Answer
FERTILISATION, ZYGOTE, BINARY, OVUM.
10
Chapter 10: Reaching the Age of Adolescence
NCERT Exercise Questions 1 to 10 (Complete)
Q1
Term for chemical secretions of endocrine glands.
1 Mark
✅ CBSE Standard Answer
Hormones
Q2
What is adolescence?
2 Marks
✅ CBSE Standard Answer
Period of life between 11-19 years leading to reproductive maturity.
Q3
What is menstruation? Explain.
3 Marks
✅ CBSE Standard Answer
Monthly breakdown and discharge of thick inner uterine lining along with blood vessels in females when egg is not fertilised.
Q4
List changes in body at puberty.
3 Marks
✅ CBSE Standard Answer
Height increase, voice change (Adam's apple in boys), sweat/acne, reproductive organs maturation.
Q5
Table of Endocrine Glands & Hormones.
3 Marks
✅ CBSE Standard Answer
Pituitary ➔ Growth Hormone; Thyroid ➔ Thyroxine; Pancreas ➔ Insulin; Adrenal ➔ Adrenalin; Testes ➔ Testosterone; Ovaries ➔ Oestrogen.
Q6
Sex hormones definition & functions.
2 Marks
✅ CBSE Standard Answer
Hormones controlling male/female secondary sexual characteristics (Testosterone in boys, Oestrogen in girls).
Q7
Balanced diet option: (ii) Chapati, dal, vegetables.
1 Mark
✅ CBSE Standard Answer
(ii) Chapati, dal, vegetables.
Q8
Notes on Adam's apple, Secondary sexual traits, Sex determination.
4 Marks
✅ CBSE Standard Answer
Adam's apple: Growing larynx in boys. Secondary traits: Facial hair, voice, breasts. Sex determination: XX = Girl, XY = Boy.
Q9
Word grid puzzle on hormones.
2 Marks
✅ CBSE Standard Answer
INSULIN, THYROXINE, ADRENALIN, TESTOSTERONE, ESTROGEN, PITUITARY.
Q10
Height growth calculation table.
2 Marks
✅ CBSE Standard Answer
Formula: (Present height / % full height) × 100.
11
Chapter 11: Force and Pressure
NCERT Exercise Questions 1 to 10 (Complete)
Q1
Push or pull changing motion examples.
2 Marks
✅ CBSE Standard Answer
Kicking a football; Applying brakes on a bicycle.
Q2
Force changing shape of object.
2 Marks
✅ CBSE Standard Answer
Squeezing dough ball; Squeezing rubber ball.
Q3
Fill in blanks: pull, friction, contact, electrostatic.
1 Mark Each
✅ CBSE Standard Answer
(a) pull (b) friction (c) contact (d) electrostatic
Q4
Archer shooting arrow blanks.
2 Marks
✅ CBSE Standard Answer
Muscular, shape, contact, gravity.
Q5
Agent & object in 4 situations.
4 Marks
✅ CBSE Standard Answer
(a) Fingers on lemon (b) Hand on tube (c) Load on spring (d) Jumper's muscles on ground.
Q6
Blacksmith hammering hot iron.
2 Marks
✅ CBSE Standard Answer
Muscular force changes shape of hot iron.
Q7
Electrostatic force in balloon pressed to wall.
2 Marks
✅ CBSE Standard Answer
Electrostatic force attracts charged balloon to wall.
Q8
Forces on plastic bucket of water held above ground.
2 Marks
✅ CBSE Standard Answer
Gravity (down) & Muscular (up) equal and opposite.
Q9
Forces on rocket launched upwards.
2 Marks
✅ CBSE Standard Answer
Gravity and Air resistance friction.
Q10
Dropper bulb pressed in water... rise of water due to...
1 Mark
✅ CBSE Standard Answer
Atmospheric pressure
12
Chapter 12: Friction
NCERT Exercise Questions 1 to 10 (Complete)
Q1
Fill in blanks: opposes, nature, heat, reduced.
1 Mark Each
✅ CBSE Standard Answer
(a) opposes (b) nature of surfaces (c) heat (d) reduced
Q2
Arrange rolling, static, sliding friction in decreasing order.
1 Mark
✅ CBSE Standard Answer
Static > Sliding > Rolling
Q3
Alida toy car friction increasing order.
2 Marks
✅ CBSE Standard Answer
Wet marble floor < Dry marble floor < Newspaper < Towel
Q4
Tilted writing desk book sliding down friction direction.
1 Mark
✅ CBSE Standard Answer
Upward along the inclined desk surface.
Q5
Soapy water on marble floor walking difficulty.
2 Marks
✅ CBSE Standard Answer
Difficult. Soap acts as lubricant reducing friction causing slipping.
Q6
Why sports persons use shoes with spikes.
2 Marks
✅ CBSE Standard Answer
Spikes increase friction and grip with ground preventing slipping.
Q7
Iqbal vs Seema pushing lighter vs heavier box.
2 Marks
✅ CBSE Standard Answer
Seema. Heavier box presses harder against floor creating higher friction.
Q8
Why sliding friction is less than static friction.
2 Marks
✅ CBSE Standard Answer
Contact points don't get enough time to interlock firmly compared to rest.
Q9
Friction as both friend and foe.
3 Marks
✅ CBSE Standard Answer
Friend: Walking, writing, braking. Foe: Wear & tear of tires/shoes, energy loss as heat.
Q10
Why objects moving in fluids must be streamlined.
2 Marks
✅ CBSE Standard Answer
Streamlined shape reduces fluid friction (drag) saving energy.
13
Chapter 13: Sound
NCERT Exercise Questions 1 to 13 (Complete)
Q1
Sound travels through solids, liquids, and gases.
1 Mark
✅ CBSE Standard Answer
(d) solids, liquids, and gases
Q2
Minimum frequency voice: A man.
1 Mark
✅ CBSE Standard Answer
(c) A man
Q3
True/False: F, T, F, T, F.
1 Mark Each
✅ CBSE Standard Answer
(a) False (b) True (c) False (d) True (e) False
Q4
Fill in blanks: Time period, Amplitude, Hertz, Noise, Frequency.
1 Mark Each
✅ CBSE Standard Answer
(a) Time period (b) Amplitude (c) Hertz (d) Noise (e) Frequency
Q5
Pendulum 40 oscillations in 4s. Frequency & Time Period.
3 Marks
✅ CBSE Standard Answer
Frequency = 40/4 = 10 Hz. Time period = 1/10 = 0.1 s.
Q6
Mosquito wing vibration 500/s. Time period.
2 Marks
✅ CBSE Standard Answer
Time period = 1/500 = 0.002 s.
Q7
Vibrating parts: Dholak, Sitar, Flute.
2 Marks
✅ CBSE Standard Answer
Dholak: Stretched membrane; Sitar: Stretched string; Flute: Air column.
Q8
Noise vs Music & can music become noise?
2 Marks
✅ CBSE Standard Answer
Noise is unpleasant sound; music is pleasing sound. Loud music becomes noise.
Q9
Noise pollution sources.
2 Marks
✅ CBSE Standard Answer
Horns, loudspeakers, factory machines, crackers.
Q10
Harmful effects of noise pollution.
2 Marks
✅ CBSE Standard Answer
Insomnia, hypertension, anxiety, hearing loss.
Q11
House on roadside vs 3 lanes away.
2 Marks
✅ CBSE Standard Answer
3 lanes away house is quieter and less polluted.
Q12
Sketch & function of Larynx.
3 Marks
✅ CBSE Standard Answer
Voice box with stretched vocal cords vibrating when air forces through slit.
Q13
Lightning seen before thunder heard. Why?
2 Marks
✅ CBSE Standard Answer
Speed of light (3×10⁸ m/s) is much faster than speed of sound (343 m/s).
14
Chapter 14: Chemical Effects of Electric Current
NCERT Exercise Questions 1 to 12 (Complete)
Q1
Fill in blanks: Conductor, Electrolysis, Cathode, Electroplating.
1 Mark Each
✅ CBSE Standard Answer
(a) Conductor (b) Electrolysis (c) Cathode (d) Electroplating
Q2
Tester dipped in solution magnetic needle deflection.
2 Marks
✅ CBSE Standard Answer
Current flowing through solution produces magnetic field deflecting needle.
Q3
Three liquids deflecting magnetic needle.
2 Marks
✅ CBSE Standard Answer
Tap water, lemon juice, vinegar.
Q4
Tester bulb not glowing reasons.
2 Marks
✅ CBSE Standard Answer
1. Non-conducting liquid 2. Loose connections 3. Dead cell 4. Current too weak.
Q5
Liquid A better conductor than Liquid B.
1 Mark
✅ CBSE Standard Answer
(a) Liquid A is a better conductor than Liquid B.
Q6
Pure water conduction & how to make it conducting.
2 Marks
✅ CBSE Standard Answer
No. Add salt, acid, or base to produce free ions.
Q7
Firemen shutting off electric supply before water hose.
2 Marks
✅ CBSE Standard Answer
Tap water conducts electricity, preventing electrocution.
Q8
Seawater vs tap water tester deflection.
2 Marks
✅ CBSE Standard Answer
Seawater has higher salt concentration conducting stronger current.
Q9
Electrician repairing outdoors in heavy rain safety.
2 Marks
✅ CBSE Standard Answer
Unsafe. Rainwater contains dissolved gases/salts conducting shock.
Q10
Rainwater testing deflection reasons.
2 Marks
✅ CBSE Standard Answer
Rainwater dissolves air pollutants (SO2, NO2) forming acidic conducting solution.
Q11
List electroplated objects.
2 Marks
✅ CBSE Standard Answer
Car bumpers, taps, bicycle handles, jewelry, tin cans.
Q12
Copper purification electroplating.
2 Marks
✅ CBSE Standard Answer
Impure copper anode (+), pure copper cathode (-), CuSO4 electrolyte.
15
Chapter 15: Some Natural Phenomena
NCERT Exercise Questions 1 to 12 (Complete)
Q1
Cannot be charged easily by friction: (b) Copper rod.
1 Mark
✅ CBSE Standard Answer
(b) A copper rod
Q2
Glass rod rubbed with silk cloth: rod positive, silk negative.
1 Mark
✅ CBSE Standard Answer
(b) rod gets positively charged, cloth negatively charged.
Q3
True/False: F, T, T, F.
1 Mark Each
✅ CBSE Standard Answer
(a) False (b) True (c) True (d) False
Q4
Crackling sound taking off sweater in winter.
2 Marks
✅ CBSE Standard Answer
Friction charges woollen sweater. Removing it causes electric discharge spark.
Q5
Charged body loses charge when touched with hand.
2 Marks
✅ CBSE Standard Answer
Human body is a conductor; charge flows to Earth (Earthing).
Q6
Richter scale 3 earthquake seismograph & damage.
2 Marks
✅ CBSE Standard Answer
Recorded by seismograph. Mild quake with low damage.
Q7
Three lightning safety measures.
2 Marks
✅ CBSE Standard Answer
1. Squat low 2. Stay away from tall trees/poles 3. Take shelter inside car/building.
Q8
Charged balloon vs uncharged balloon.
2 Marks
✅ CBSE Standard Answer
Like charges repel. Charged balloon induces opposite charge on uncharged balloon attracting it.
Q9
Electroscope instrument working.
3 Marks
✅ CBSE Standard Answer
Metal clip holding two aluminium foil leaves in jar. Charge transfers down clip ➔ leaves repel & diverge.
Q10
Three earthquake prone states in India.
1 Mark
✅ CBSE Standard Answer
Gujarat, J&K, Assam.
Q11
Earthquake precautions outdoors.
2 Marks
✅ CBSE Standard Answer
Move to clear open ground away from buildings, trees, electric wires.
Q12
Carrying umbrella in thunderstorm safe?
2 Marks
✅ CBSE Standard Answer
No. Metallic rod & top tip attract lightning strikes.
16
Chapter 16: Light
NCERT Exercise Questions 1 to 17 (Complete)
Q1
Dark room seeing objects inside vs outside.
2 Marks
✅ CBSE Standard Answer
Cannot see inside dark room (no light reflection). Can see outside if light present.
Q2
Regular vs Diffused reflection & laws of reflection.
2 Marks
✅ CBSE Standard Answer
Regular on smooth mirror; diffused on rough surface. Diffused is not failure of laws.
Q3
Regular or Diffused for 6 surfaces.
2 Marks
✅ CBSE Standard Answer
Polished table: Regular; Chalk powder: Diffused; Cardboard: Diffused; Wet marble: Regular; Mirror: Regular; Paper: Diffused.
Q4
State laws of reflection.
2 Marks
✅ CBSE Standard Answer
1. Angle of incidence (∠i) = Angle of reflection (∠r). 2. Incident ray, reflected ray, and normal lie in same plane.
Q5
Activity for incident ray, reflected ray, normal in same plane.
3 Marks
✅ CBSE Standard Answer
Fix paper on table, shine light onto mirror. Bending paper projecting beyond edge causes reflected ray to disappear on bent portion.
Q6
Fill in blanks: 1m, Left ear, Pupil, Rods, Cones.
1 Mark Each
✅ CBSE Standard Answer
(a) 1 m (b) Left ear (c) Pupil (d) Rods (e) Cones
Q7
Angle of incidence = Angle of reflection: (a) Always.
1 Mark
✅ CBSE Standard Answer
(a) Always
Q8
Image formed by plane mirror: (a) Virtual, behind mirror, same size.
1 Mark
✅ CBSE Standard Answer
(a) Virtual, behind mirror, same size as object.
Q9
Construction of Kaleidoscope.
3 Marks
✅ CBSE Standard Answer
Three mirror strips joined at 60° angles inside tube with glass pieces forming symmetrical patterns.
Q10
Labelled sketch & parts of Human Eye.
3 Marks
✅ CBSE Standard Answer
Cornea, Iris, Pupil, Lens, Retina, Optic Nerve.
Q11
Why laser torch dangerous for eyes.
1 Mark
✅ CBSE Standard Answer
High laser intensity permanently burns retina cells.
Q12
How to take care of eyes.
2 Marks
✅ CBSE Standard Answer
Clean water wash, read in proper light, avoid direct sun, eat Vitamin A diet.
Q13
Angle of incidence if reflected ray at 90°.
2 Marks
✅ CBSE Standard Answer
∠i + ∠r = 90° ➔ 2∠i = 90° ➔ ∠i = 45°.
Q14
Candle between parallel mirrors.
1 Mark
✅ CBSE Standard Answer
Infinite number of images
Q15
Mirrors at 90°, incident ray 30°.
2 Marks
✅ CBSE Standard Answer
Reflection from 1st = 30°. Incident 2nd = 60°. Reflected 2nd = 60°.
Q16
Boojho at A seeing images of P, Q, R.
2 Marks
✅ CBSE Standard Answer
Boojho sees images of P and Q, but not R. Cannot see himself.
Q17
Position of image of object A & Paheli/Boojho seeing it.
2 Marks
✅ CBSE Standard Answer
(a) Perpendicular behind mirror at same distance. (b) Paheli can see it. (c) Boojho can see it. (d) Image position does NOT move.
🎉
Every Single Question of All 16 Chapters Included!
All 183 exercise questions from Chapter 1 to 16 are present with official CBSE standard solutions.