JEE 2020 Physics: Thermal Properties of Matter Quiz (02.07.2019) for JEE & BITSAT Exams

Question 1

The specific heat capacity of a metal at low temperature (T) is given as

. A 100 gram vessel of this metal is to be cooled from 20 K to 4 K by a special refrigerator operating at room temperature (27ºC). The amount of work required to cool the vessel is :

Question 2

An aluminum sphere of 20 cm diameter is heated from 0ºC to 100ºC. Its volume changes by (given that coefficient of linear expansion for aluminum α_AI = 23 × 10^-6/ºC)

Question 3

Two different liquids of same mass are kept in two identical vessels, which are placed in a freezer that extracts heat from them at the same rate causing each liquid to transform into a solid. The schematic figure below shows the temperature T vs time t plot for the two materials. We denote the specific heat of materials in the liquid (solid) states to be CL₁ (CS₁) and CL₂ (CS₂) respectively.

Choose the correct option.

Question 4

A planet of radius

is revolving around a star of radius

which is at temperature

The distance between the star and the planet is

If the planet’s temperature is

then

is proportional to

Question 5

Two different liquids of same mass are kept in two identical vessels, which are placed in a freezer that extracts heat from them at the same rate causing each liquid to transform into a solid. The schematic figure below shows the temperature

vs time

plot for the two materials.
We denote the specific heat in the liquid states to be

and

for materials 1 and 2 respectively, and latent heats of fusion

and

respectively.

Choose the correct option.

Question 6

The figure shows a system of two concentric spheres of radii r₁ and r₂ and kept at temperatures, T₁ and T₂, respectively. The radial rate of flow of heat in a substance between the two concentric spheres is proportional to

Question 7

The pressure that has to be applied to the ends of a steel wire of length 10 cm to keep its length constant when its temperature is raised by 100 °C is :
(For steel Young's modulus is 2x 10¹¹ Nm^-2 and coefficient of thermal expansion is 1.1 × 10^-5 K^-1)

Question 8

Three rods of Copper Brass and Steel are welded together to from a Y-shaped structure. Area of cross section of each rod = 4 cm² . End of copper rod is maintained at 100 °C where as ends of brass and steel are kept at 0 °C. Lengths of the copper, brass and steel rods are 46. 13 and 12 cms respectively. The rods are thermally insulated from surroundings except at ends. Thermal conductivities of copper, brass and steel are 0.92, 0.26 and 0.12 CGS units respectively. The rate of heat flow through copper rod is

Question 9

A liquid in a beaker has temperature θ (t) at time t and θ₀ is temperature of surroundings, then according to Newton’s law of cooling the correct graph between log_e (θ - θ₀) and t is

Question 10

A liquid in a beaker has temperature θ (t) at time t and θ₀ is temperature of surroundings, then according to Newton’s law of cooling the correct graph between log_e (θ - θ₀) and t is