MCQ On Class 11 Physics Chapter 11 Thermal Properties of Matter

1 A person with dark skin as compared to a person with white skin will experience

A Less heat and less cold

B More heat and more cold

C More heat and less cold

D Less heat and more cold.

View Answer

Answer:More heat and more cold

2 The best ideal black body is

A Lamp of charcoal heated to high temperature

B Metal coated with a black dye

C Glass surface coated with coalter

D Hollow enclosure blackened inside and having a small hole

View Answer

Answer:Hollow enclosure blackened inside and having a small hole

3 The process of heat transfer in which heat is transferred with actual migration of medium particles is known as (AFMC-94)

A Conduction

B Convection

C Radiation

D Reflection

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Answer:Convection

4 The flow of heat from a hot body to a cold body is an example of

A Isothermal process

B Reversible process

C Adiabatic process

D Irreversible process

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Answer:Irreversible process

5 A black body at hot temperature at 227°C radiates heat at a rate of 5 cal/cm²s. at a temperature of 727°C the rate of heat radiated per unit area will be

A 50 cal/cm²s

B 250 cal/cm²s

C 80 cal/cm²s

D 100 cal/cm²s

View Answer

Answer:80 cal/cm²s

6 A bucket full of hot water is kept in a room and it cools from 75°C to 70°C in t1 minutes from 70°C to 65°C in t2 minutes and from 65°C to 60°C in t3 minutes; then

A t1 – t2 = t3

B t1 < t2 < t3

C t1 > t2 > t3

D t1 < t2 > t3

View Answer

Answer:t1 < t2 < t3

7 Two stars A and B radiate maximum energy at 3600°A and 3600°A respectively. Then the ratio of absolute temperatures of A and B is

A 256 : 81

B 81 : 256

C 3 : 4

D 4 : 3

View Answer

Answer:4 : 3

8 A cup of tea cools from 80°C to 60°C in one minute. The ambient temperature is 30°C. in cooling from 60°C to 50°C, it will take.

A 50 sec

B 90 sec

C 60 sec

D 30 sec

View Answer

Answer:50 sec

9 Unit of Stefans constant is given by

A W/ m K²

B W/ m² K²

C W²/ m² K4

D W/ mK

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Answer:W/ m² K²

10 The earth receives at its surface radiation from the sun at the rate of 1400 W/m². the distance of the centre of the sun from the surface of the earth is 1.5 1011 m and the radius of the sun is 7.0 108 m. treating sun as a black body, it follows from the above data that its surface temperature is,

A 5801 K

B 106 K

C 50.1 K

D 2801 C

View Answer

Answer:5801 K

11 The temperature of a piece of metal is raised from 27°C to 51.2°C. the rate at which metal radiates energy increases nearly

A 1.36 times

B 2.36 times

C 3.36 times

D 4.36 times

View Answer

Answer:1.36 times

12 The earth intercepts approximately one billionth of the power radiated by the sun. if the surface temperature of the sun were to drop by a factor of 2, the average radiant energy incident on earth per second would reduce by factor of

A 2

B 4

C 8

D 16

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Answer:16

13 Emissivity of perfectly black body is

A 1

B 2

C 5

D 0

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Answer:1

14 A body cools from 50°C to 46°C in 5 minutes and to 40°C in the next 10 minutes. The surrounding temperature is

A 30°C

B 28°C

C 36°C

D 32°C

View Answer

Answer:30°C

15 Absorptive power of perfectly black body is

A Zero

B Infinity

C One

D Constant

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Answer:One

16 For which of the following process, the thermal conduction is maximum?

A Combustion

B Radiation

C Convection

D Conduction

View Answer

Answer:Radiation

17 A metal piece heated to T1°K. The temperature of the surrounding is T2°K. the heat in the surrounding due to radiation is proportional to

A (T14 – T24)

B (T1 – T2)4

C (T14 + T24)

D (T13 – T23)

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Answer:(T14 – T24)

18 A surface at temperature T0°K receives power P by radiation from a small sphere at temperature T >> T0 and at a distance d. if both T and d are doubled, the power received by surface will becomes approximately

A P

B 2p

C 4p

D 16p

View Answer