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30 important science questions for UPSC exams

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Important Science Questions For UPSC

In this blog, we’ll delve into 30 important science questions that aspirants can expect in the UPSC exams. Each question is strategically designed to test your understanding and elevate your readiness for the UPSC journey.

1. German silver used for making utensils is an alloy of

a. copper, silver, nickel

b. copper, zinc, nickel

c. copper, zinc, aluminum

d. copper, nickel, aluminum

2. Aqua regia is a 1 : 3 mixture, by volume, of

a. conc. nitric acid and conc. hydrochloric acid

b. conc. hydrochloric acid and conc. nitric acid

c. conc. nitric acid and conc. sulphuric acid

d. conc. sulphuric acid and conc. nitric acid

3. In upper layer of atmosphere ozone is formed by

a. the action of ultraviolet rays on oxygen

b. the combination of oxygen molecules

c. subjecting oxygen to high pressure

d. the action of nitrogen on oxygen in atmosphere

4. Which one of the following is used as preservative for food stuff ?

a. Sodium Benzoate

b. Picric acid

c. Glycerine

d. Sodium Chloride

5. Electrolysis of an aqueous solution of copper sulphate using copper electrodes gives

a. Copper at cathode and oxygen at anode.

b. Copper at anode and oxygen at cathode.

c. Copper at cathode and anodes dissolve to give copper.

d. Hydrogen at cathode and oxygen at anode.

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6. Sodium Carbonate is commonly known as

a. Baking Soda

b. Washing Soda

c. Caustic Soda

d. Caustic Potash

7. All isotopes of the same element have 

a. different atomic numbers and different atomic mass

b. different atomic numbers and the same atomic mass

c. the same atomic number but different atomic masses

d. the same atomic number and the atomic mass

8. Metal are good conductors, because

a. they contain free electrons

b. the molecules in them are very close to each other

c. the molecules in them collide very freely

d. they contain reflecting surface

9. When conc. H 2 SO 4 is added to dry KNO 3 , brown fumes are evolved. These fumes are  due to

a. SO 3

b. SO 2

c. NO 2

d. N 2O

10. The lustre of the metals is because of

a. high density, due to closed packing of atoms

b. high polish

c. reflection of light due to the presence of free electrons

d. absorption of light due to the presence of cavities

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11. When light passes from one medium to another medium, which one of the following does not change? 

a. Intensity 

b. Velocity 

c. Wavelength 

d. Frequency

12. Kerosene oil rises up in a wick of a lantern because of 

a. diffusion of the oil through the wick 

b. capillary action 

c. buoyant force of air 

d. the gravitational pull of the wick

13. A body travelling with a speed of more than the velocity of sound in air is said to travel with 

a. supersonic speed 

b. hypersonic speed 

c. ultrasonic speed 

d. infrasonic speed

14. When the distance between the object and the plane mirror increases 

a. the image remains same 

b. the size of the image will become less than the size of the object 

c. the distance between the image and the plane mirror increases 

d. the distance between the image and the plane mirror decreases

15. What should be the characteristic of fuse wire? 

a. High melting point, high specific resistance 

b. Low melting point, low specific resistance 

c. High melting point, low specific resistance 

d. Low melting point, high specific resistance 

16. Consider the following statements and select the correct code:

Assertion (A): A piece of ice added to the drink cools it.

Reason (R): Ice takes latent heat from the drink for melting resulting in the cooling of the drink.


a. Both A and R are true, and R is the correct explanation of A.

b. Both A and R are true, but R is not the correct explanation of A.

c. A is true, but R is false.

d. A is false, but R is true

17. Consider the following statements:

1. Two persons on the surface of moon cannot talk to each other.

2. Sound waves cannot travel through vacuum.

3. Speed of sound is greater in solid medium than in liquid or gas medium.

a. Only 3 is correct

b. 1 and 2 are correct

c. 1 and 3 are correct

d. 1, 2 and 3 are correct

18. Consider the following statements:

1. A flute of smaller length produces waves of lower frequency.

2. Sound travels in rocks in the form of longitudinal elastic waves only.

Which of the statement(s) given above is/are correct?

a. 1 only

b. 2 only

c. Both 1 and 2

d. Neither 1 nor 2

19. Refractive index of an optical medium changes with

1. the nature of the medium.

2. the change in the angle of incidence of the ray.

3. colour of the incident ray.

a. 1 only

b. 2 only

c. Both 1 and 2

d. Neither 1 nor 2

20. Which one of the following is the correct sequence of the given substances in the decreasing order of their densities?

a. Steel > Mercury > Gold

b. Gold > Mercury > Steel

c. Steel > Gold > Mercury

d. Gold > Steel > Mercury

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21. Yawning occurs

a. due to excess concentration of CO 2 in blood

b. due to excess concentration of CO 2 in lungs

c. due to excess concentration of O 2 in lungs

d. None of these

22. What is the number of chromosomes in a normal human body cell ?

a. 43 

b. 44

c. 45 

d. 46

23. Clove, the commonly used spice, is obtained from the

a. root 

b. stem

c. flower bud 

d. fruit

24. What is the approximate time required for a heart-beat ?

a. 0.5 second 

b. 0.8 second

c. 0.5 minute 

d. 1.0 minute

25. Correlate the following 


A. Green leafy vegetables

B. Raw cabbage

C. Brewers yeast

D. Wheat-germ oil


1. A 

2. B1

3. C 

4. D

5. E


a. 1 2 3 4

b. 1 3 2 5

c. 2 3 4 5

d. 2 4 5 1

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26. M.R.I. stands for

a. Metered Resonance Imaging

b. Magnetic Resonance Imaging

c. Magnetic Reaction Imaging

d. Metered Reaction Imaging

27. Which one of the following set belongs to the class Mammalia ?

a. Lion, Hippopotamus, Penguin, Bat.

b. Lion, Bat, Whale, Ostrich

c. Hippopotamus, Penguin, Whale, Kangaroo

d. Whale, Bat, Kangaroo, Hippopotamus

28. Which one of the following is not transmitted via blood transfusion?

a. Hepatitis 

b. Typhoid

c. HIV

d. Malaria

29. Flat footed camels can walk easily in sandy deserts because

a. pressure on the sand is decreased by increasing the area of the surface in contact

b. pressure on the sand is increased by increasing the area of the surface in contact

c. pressure on the sand is decreased by decreasing the area of the surface in contact

d. pressure on the sand is increased by decreasing the area of the surface in contact

30. Which of the following is correct about cold blooded animals ?

a. Their blood remains cold all the time

b. Their body temperature changes in accordance with the atmosphere

c. Their body temperature remains constant all the time

d. They kill all the animals they come across

Above questions are taken from “5000+ Most Expected MCQs” book. It’s filled with tons of multiple-choice questions designed for the UPSC exams. This book will help you get used to the kinds of questions you’ll see on the actual test and make sure you’re totally ready. So, grab a copy and get practicing.

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DDE editor
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