CBSE Questions for Class 7 Physics Heat Quiz 7 - MCQExams.com

Statement-1
Radiation involves transfer of heat by electromagnetic waves.
Statement-2
Electromagnetic waves do not required any material medium for propagation.
  • Statement-1 is true, Statement-2 is true and Statement-2 is the correct explanation for Statement-1.
  • Statement-1 is true, Statement-2 is true but Statement-2 is not the correct explanation for Staement-1.
  • Statement-1 is true, Statement-2 is false.
  • Statement-1 is false, Statement-2 is true.
The lowest attainable fahrenheit temperature is
  • $$-100^{\circ} F$$
  • $$-459.4^{\circ} F$$
  • $$-300^{\circ} F$$
  • $$-373.2^{\circ} F$$
For an ideal conductor, thermal resistance is :
  • unity
  • infinity
  • zero
  • 1000
The process in which rate of transfer of heat is maximum is :
  • conduction
  • convection
  • radiation
  • in all these, heat is transferred with the same speed
Which of the follwing is the smallest rise in temperature?
  • $$1^{\circ}F$$
  • $$1K$$
  • $$1^{\circ}C$$
  • All are of equal value
If we place our hand below a lighted electric bulb. We feel warmer because of :
  • convection
  • radiation
  • conduction
  • both A and B

The temperature at which a body does not radiate energy
  • $$0^{0}$$C
  • $$0\ K$$
  • $$273\ K$$
  • $$4^{0}$$ C
Solids get heated by
  • Conduction
  • Convection
  • Radiation
  • None
Name the temperature scale used in S.I. system.
  • Kelvin scale
  • Celsius scale
  • Fahrenheit scale
  • All of the above
Which metal is a good conductor of heat?
  • Gold
  • Carbon
  • Lead
  • Alloys
The thermodynamic scale of temperature was given by
  • Dewar
  • Fahrenheit
  • Kelvin
  • Carnot
State true or false:
The more is the temperature difference of hot and cold body more slowly the heat flows from it into the cold body
  • True
  • False
Choose the correct experiment to demonstrate the transfer of heat by the process of conduction.
  • Take two metal blocks of same size & shape and heat one of them to a considerable temperature, then allow both the blocks to touch each other, after a while, you will see the other block gets heated due to contact.
  • Take two metal blocks of same size & shape and heat one of them to a considerable temperature, then keep the blocks separate, after a while you will see the other block gets heated due to contact.
  • Take two metal blocks of same size & shape and heat one of them to a considerable temperature, then allow both the blocks to touch each other after the block get cooled down, after a while you will see the other block gets heated due to contact.
  • None of above
The measure of degree of hotness or coldness of a body is called:
  • Heat energy
  • Celsius
  • Kelvin
  • Temperature
Complete the following sentences:
(a) Metals are ............. conductors of heat, while gases are ............ conductors of heat.
(b) Water is a ............ conductor of heat, while silver is a ................ conductor of heat.
(c) Silver is ............... conductor of heat than iron.
  • (a) good, bad

    (b) very poor, good

    (c) a better
  • (a) good, bad

    (b) very good, good

    (c) a better
  • (a) bad, good

    (b) very poor, good

    (c) a better
  • (a) good, bad

    (b) very poor, bad

    (c) a better
When two bodies at different temperatures are placed in thermal contact with each other, heat flows from the body at a higher temperature until they both acquire the same temperature. Assuming that there is no loss of heat to the surroundings, then:
  • The heat gained by the hotter body will be equal to the heat lost by the colder body
  • The heat gained by the hotter body will be less than the heat lost by the colder body
  • The heat gained by the hotter body will be greater than the heat lost by the colder body
  • The heat lost by the hotter body will be equal to the heat gained by the colder body.
The range of a clinical thermometer is
  • 0-100$$^0$$C
  • 32-214$$^0$$F
  • 0-1273$$^0$$C
  • 35-42$$^0$$C
The rise in temperature of a substance depends on
  • the quantity of heat supplied
  • the mass of the substance
  • the nature of the substance
  • all the above
A red hot brick is placed on an iron tripod stand which stands on a large block of copper. The brick loses heat by:
  • conduction
  • conduction and radiation
  • conduction and convection
  • conduction, convection, and radiation
Suppose a liquid in a container is heated at the top rather than at the bottom. What is the main process by which the rest of the liquid becomes hot ?
  • Conduction
  • Evaporation
  • Sublimation
  • None of these
At low temperatures ................. type of thermometer is used.
  • mercury thermometer
  • water thermometer
  • alcohol thermometer
  • thermometers cannot be used
When you heat a bowl of water, we can observe that water starts circulating. This demonstrates:
  • conduction
  • convection
  • radiation
  • none
In the diagram shown, will the convection current be clockwise or anticlockwise on the left part of the figure?
268379_edcd876dd6ec47ef8f0b9506232fa4f4.png
  • Anticlockwise
  • Clockwise
  • Will keep on changing
  • Can't be said
The water in an open pond remains cool even in hot summer because
  • of continuous evaporation of water
  • water radiates heat more rapidly than the atmosphere
  • water being bad conductor absorbs heat less rapidly than the atmosphere
  • None of these
It is hotter over the top of fire than at the same distance on the sides because of:
  • Convection of heat
  • Conduction of heat
  • Radiation of heat
  • All of the above
Air is a good conductor of heat.
  • True
  • False
Which of the following is the coldest temperature possible?
  • 0K
  • $$0^{\circ}$$C
  • $$0^{\circ}$$F
  • $$-273^{\circ}$$F
The most commonly used thermometric substance is
  • water
  • alcohol
  • mercury
  • steam
Mud houses are cooler in summer and warmer in winter because
  • mud is a good conductor of heat
  • mud is a superconductor of heat
  • mud is a bad conductor of heat
  • none of these
Woollen sweaters keep us warm because:
  • Wool is a poor conductor of heat
  • Air is trapped in between the fibres
  • Both A and B
  • None of these
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