Heat And Thermodynamics PYQs — 11 UPSC CSE Previous Year Questions

Question 1

In a pressure cooker, the temperature at which the food is cooked depends mainly upon which of the following? Area of the hole in the lid Temperature of the flame Weight of the lid Select the correct answer using the code given below.

Accepted Answer

C. 1 and 3 only

Question 2

The surface of a lake is frozen in severe winter, but the water at its bottom is still liquid. What is the reason ?

Accepted Answer

C. The density of water is maximum at 4°C

Question 3

Which one of the following is printed on a commonly used fluorescent tube light?

Accepted Answer

C. 6500 K

Question 4

Consider the following statements:

Steam at 100°C and boiling water at 100°C contain same amount of heat.
Latent heat of fusion of ice is equal to the latent heat of vaporization of water.
In an air-conditioner, heat is extracted from the room air at the evaporator coils and is rejected out at the condenser coils.

Which of these statements is/are correct?

Accepted Answer

D. Only 3

Question 5

A hollow sphere of radius R, a hollow cube of side R and a thin circular plate of radius R, made up of the same material, are all heated to 20°C above room temperature. When left to cool in the room, which of them will reach the room temperature first?

Accepted Answer

C. Sphere

Question 6

When water is heated from 0ºC to 10ºC, its volume:

Accepted Answer

D. first decreases and then increases

Question 7

Assertion (A): The boiling point of water decreases as the altitude increases. Reason (R): The atmospheric pressure increases with altitude. Codes:

Accepted Answer

C. A is true but R is false

Question 8

Assertion (A): A piece of copper and a piece of glass are heated to the same temperature. When touched, thereafter, the copper piece appears hotter than the glass piece. Reason (R): The density of copper is more than that of glass. Codes:

Accepted Answer

B. Both A and R are true and R is not a correct explanation of A

Question 9

Assertion (a) : To dih4te sulphuric acid, acid is added to water and not water to acid. Reason (K) : Specific heat of water is quite 1arge

Accepted Answer

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

Question 10

Consider the following statements:

An ordinary light bulb has a rather short life because the:

filament wire is not uniform.
bulb cannot be evacuated completely.
wires supporting the filament melt at high temperatures.

Which of the above statements are correct?

Accepted Answer

D. 1, 2 and 3