CBSE Class 11 Physics – MCQ and Online Tests – Unit 11 – Thermal Properties of Matter
Every year CBSE schools conducts Annual Assessment exams for 6,7,8,9,11th standards. These exams are very competitive to all the students. So our website provides online tests for all the 6,7,8,9,11th standard’s subjects. These tests are also very effective and useful for those who preparing for any competitive exams like Olympiad etc. It can boost their preparation level and confidence level by attempting these chapter wise online tests.
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CBSE Class 11 Physics – MCQ and Online Tests – Unit 11 – Thermal Properties of Matter
Question 1.
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
Answer
Answer: (d) 16
Question 2.
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
Answer
Answer: (b) Convection
Question 3.
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
Answer
Answer: (a) 30°C
Question 4.
For which of the following process, the thermal conduction is maximum?
(a) Combustion
(b) Radiation
(c) Convection
(d) Conduction
Answer
Answer: (b) Radiation
Question 5.
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
Answer
Answer: (b) t1 < t2 < t3
Question 6.
The good absorber of heat are
(a) Non-emitter
(b) Poor-emitter
(c) Good-emitter
(d) Highly polished
Answer
Answer: (c) Good-emitter
Question 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
Answer
Answer: (d) 4 : 3
Question 8.
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.
Answer
Answer: (b) More heat and more cold
Question 9.
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
Answer
Answer: (a) 50 sec
Question 10.
Unit of Stefans constant is given by
(a) W/ m K²
(b) W/ m² K²
(c) W²/ m² K4
(d) W/ mK
Answer
Answer: (b) W/ m² K²
Question 11.
The good absorber of heat are
(a) Non-emitter
(b) Poor-emitter
(c) Good-emitter
(d) Highly polished
Answer
Answer: (c) Good-emitter
Question 12.
Co-efficient of reflection, coefficient of absorption and coefficient transmission are related as
(a) a + r + 1 = 1
(b) a + r + t1 1
(c) a + r = -t
(d) a1 r + 1
Answer
Answer: (a) a + r + 1 = 1
Question 13.
Absorptive power of perfectly black body is
(a) Zero
(b) Infinity
(c) One
(d) Constant
Answer
Answer: (c) One
Question 14.
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
Answer
Answer: (c) 80 cal/cm²s
Question 15.
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)
Answer
Answer: (a) (T14 – T24)
Question 16.
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
Answer
Answer: (a) 5801 K
Question 17.
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
Answer
Answer: (c) 4p
Question 18.
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
Answer
Answer: (a) 1.36 times
Question 19.
Emissivity of perfectly black body is
(a) 1
(b) 2
(c) 5
(d) 0
Answer
Answer: (a) 1
Question 20.
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
Answer
Answer: (d) Hollow enclosure blackened inside and having a small hole
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