Class 10 Science
Previous Board Examination – Full Solved Answers (Set 3)
The following answers are written in simple student language as expected in the CBSE Board Examination to score full marks.
Section A – MCQs (Answers)
1. Ammonia
2. Chloroplast
3. Ohm
4. Mercury
5. At infinity
6. O
7. Carbon dioxide
8. Potential energy
9. Semicircular canals
10. Less than 7
Section B – Very Short Answer
11. Define chlorophyll.
Chlorophyll is the green pigment present in leaves that helps plants to trap sunlight for photosynthesis.
12. Write the chemical formula of quick lime.
The chemical formula of quick lime is CaO.
13. Define electric resistance.
Electric resistance is the property of a conductor that opposes the flow of electric current through it.
14. What is pollination?
Pollination is the transfer of pollen grains from the anther to the stigma of a flower.
15. Name the hormone that controls growth in humans.
The hormone that controls growth in humans is Growth hormone.
Section C – Short Answer
16. Explain the process of digestion in human beings.
Digestion in humans takes place in the alimentary canal:
- Mouth: Food is chewed and mixed with saliva.
- Stomach: Food is mixed with digestive juices.
- Small intestine: Digestion is completed and nutrients are absorbed.
- Large intestine: Water is absorbed.
17. Write three uses of acids.
- Used in batteries.
- Used in manufacturing fertilisers.
- Used in food preservation.
18. State Joule’s law of heating.
Joule’s law of heating states that heat produced in a conductor is directly proportional to:
- Square of current (I²)
- Resistance (R)
- Time (t)
H = I²Rt
19. Describe the structure of lungs.
The lungs are spongy organs present in the chest cavity.
- They contain alveoli.
- Alveoli increase surface area for gas exchange.
- Oxygen enters blood and carbon dioxide leaves blood.
(Draw neat labelled diagram of lungs)
20. Explain refraction of light with example.
Refraction of light is the bending of light when it passes from one medium to another.
Example: A pencil appears bent when placed in water.
21. What is biodegradable waste? Why is it important?
Biodegradable waste is waste that can be decomposed by microorganisms.
It is important because it reduces pollution and can be recycled naturally.
Section D – Long Answer
22. Explain nutrition in human beings.
Nutrition in humans is heterotrophic.
- Ingestion – taking food
- Digestion – breaking food into simpler substances
- Absorption – nutrients absorbed in intestine
- Assimilation – use of nutrients
- Egestion – removal of waste
23. Describe sexual reproduction in plants.
Sexual reproduction in plants involves:
- Pollination
- Fertilisation
- Seed formation
Seeds germinate to form new plants.
24. Derive the formula for electric power.
Electric power is the rate of doing work.
P = VI
Using V = IR,
P = I²R
25. Explain the working of a concave mirror.
A concave mirror converges parallel rays of light to its focus.
- Used in torches and headlights.
- Forms real and inverted images.
(Draw ray diagram)
Section E – Case Study Based
26.
a) It is a chemical change.
b) Lactic acid is formed.
c) Refrigeration prevents this change.
Shaktimatha CBSE Learning
Class 10 Science – Previous Board Exam Full Answers (Set 3)
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