Class 10 Science
Previous Board Examination – Full Solved Answers (Set 2)
The answers below are written in simple student writing style, exactly as expected in CBSE board examinations.
Section A – MCQs (Answers)
1. Convex mirror
2. NaHCO3
3. Oxygen
4. Ohm
5. Cerebrum
Section B – Very Short Answer
6. Define focal length of a lens.
The distance between the optical centre of a lens and its principal focus is called its focal length.
7. What is a balanced chemical equation?
A chemical equation in which the number of atoms of each element is equal on both sides is called a balanced chemical equation.
8. Name the female reproductive part of a flower.
Pistil (Carpel)
9. What is meant by electric power?
Electric power is the rate at which electrical energy is consumed or converted into other forms of energy.
10. Write one function of bile juice.
Bile juice helps in the digestion of fats by emulsifying them.
Section C – Short Answer
11. State the laws of refraction of light.
1. The incident ray, refracted ray and the normal at the point of incidence lie in the same plane.
2. The ratio of sine of angle of incidence to sine of angle of refraction is constant for a given pair of media.
12. Explain the process of neutralisation with an example.
Neutralisation is the reaction between an acid and a base to form salt and water.
Example: HCl + NaOH → NaCl + H2O
13. What is vegetative propagation? Write one advantage.
Vegetative propagation is a type of asexual reproduction in which new plants grow from parts like root, stem or leaf.
Advantage: It produces plants identical to the parent plant.
14. Write any three differences between acids and bases.
1. Acids turn blue litmus red, while bases turn red litmus blue.
2. Acids are sour in taste, while bases are bitter.
3. Acids release H+ ions, while bases release OH− ions.
15. What is meant by reflex action? Give one example.
Reflex action is a sudden and automatic response to a stimulus.
Example: Pulling back the hand on touching a hot object.
16. Define magnification. Write its formula.
Magnification is the ratio of the height of the image to the height of the object.
Magnification (m) = hi / ho
Section D – Long Answer
17. Explain the formation of image by a concave mirror.
A concave mirror forms images depending on the position of the object.
When the object is placed beyond the centre of curvature, the image is formed between C and F. It is real, inverted and diminished.
18. Describe the preparation of washing soda.
Washing soda is prepared from baking soda by heating it.
2NaHCO3 → Na2CO3 + H2O + CO2
The sodium carbonate obtained is then recrystallised to form washing soda.
19. Explain respiration in human beings.
Respiration is the process of breaking down food to release energy.
In humans, oxygen is inhaled into lungs and carbon dioxide is exhaled. Oxygen is used to oxidise glucose and release energy.
20. State and explain Joule’s law of heating.
According to Joule’s law, heat produced in a conductor is directly proportional to the square of current, resistance and time.
H = I2Rt
Section E – Case Study Based
21.
a) Heating effect of electric current
b) Used in electric heaters and irons
c) Causes wastage of energy
Shaktimatha CBSE Learning
Class 10 Science – Previous Board Exam Full Answers (Set 2)
⬅️ Back to Class 10 Science Library
🔬 Class 10 Science – Previous Board Question Papers & Full Answers
This complete library is designed for Class 10 CBSE students to practise previous board exam papers and learn how to write perfect answers in Physics, Chemistry, and Biology.
📝 Previous Board Question Papers
- Question Paper – Set 1
- Question Paper – Set 2
- Question Paper – Set 3
- Question Paper – Set 4
- Question Paper – Set 5
✍️ Full Answers (Student Writing Style)
- Full Answers – Set 1
- Full Answers – Set 2
- Full Answers – Set 3
- Full Answers – Set 4
- Full Answers – Set 5
📚 Additional Board Sets (Practice)
- Additional Question Paper – Set 1A
- Additional Full Answers – Set 1A
- Additional Question Paper – Set 2A
- Additional Full Answers – Set 2A
- Additional Question Paper – Set 3A
- Additional Full Answers – Set 3A
✔ First attempt the question paper on your own
✔ Then compare with full answers
✔ Observe diagrams, keywords, and steps
✔ Practise again to improve speed and accuracy
Prepared with dedication by Shaktimatha Learning ✨
Clear concepts • Exam confidence • Board success
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