Heat Class 7 MCQ with Answers. We covered all the Heat Class 7 MCQ with Answers in this post for free so that you can practice well for the exam.
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MCQ on Heat for Class 7 Students
At a certain temperature for a given wavelength, the ratio of the emissive power of a body to the emissive power of a black body in the same circumstances is known as
(a) relative emissivity
(b) emissivity
(c) absorption coefficient
(d) coefficient of reflection
Option c – absorption coefficient
When a body is heated, which color corresponds to high temperature
(a) red
(b) yellow
(c) white
(d) orange
Option c – white
If the color of the star is changing from red to blue it means
(a) the star is going away from the earth
(b) the star is coming near the earth
(c) the star is stationary
(d) None of these
Option b – the star is coming near the earth
The radiation emitted by a perfectly black body is proportional to
(a) the temperature on the ideal gas scale
(b) the fourth root of temperature on the ideal gas scale
(c) the fourth power of temperature on the ideal gas scale
(d) square of temperature on an ideal gas scale
Option c – the fourth power of temperature on the ideal gas scale
Newton’s law of cooling is a special case of
(a) Stefan’s law
(b) Kirchhoff’s law
(c) Wien’s law
(d) Plank’s law
Option a – Stefan’s law
Newton’s law of cooling holds good only if the temperature difference between the body and the surrounding is
(a) less than 10°C
(b) more than 10°C
(c) less than 100°C
(d) more than 100°C
Option a – less than 10°C
The first law of thermodynamics expresses
(a) law of conservation of momentum
(b) the law of conservation of energy
(c) the law of conservation of mass
(d) All of the above
Option b – the law of conservation of energy
The first law of thermodynamics is a special case of
(a) Newton’s law
(b) the law of conservation of energy
(c) Charle’s law
(d) the law of heat exchange
Option b – the law of conservation of energy
Thermodynamics is concerned in part with transformations between
(a) different forms of heat energy
(b) internal energy at various temperatures
(c) one form of mechanical energy into other forms
(d) heat, internal energy, and mechanical work
At a given temperature the internal energy of a substance
(a) in the liquid state is equal to that in a gaseous state.
(b) in the liquid state is less than that in a gaseous state.
(c) in the liquid state is more than that in a gaseous state.
(d) is equal for the three states of matter.
Option b – in the liquid state is less than that in a gaseous state
Which of the following is incorrect regarding the first law of thermodynamics?
(a) It is a restatement of the principle of conservation of energy.
(b) It is applicable to cyclic processes
(c) It introduces the concept of entropy
(d) It introduces the concept of internal energy
Option c – It introduces the concept of entropy
The internal energy of an ideal gas does not depend upon
(a) the temperature of the gas
(b) the pressure of the gas
(c) the atomicity of the gas
(d) the number of moles of the gas.
Option b – the pressure of the gas
The air conditioner is based on the principle of
(a) Carnot cycle
(b) refrigerator
(c) the first law of thermodynamics
(d) None of these
Option b – refrigerator
Which of the following processes is reversible?
(a) Transfer of heat by conduction
(b) Transfer of heat by radiation
(c) Isothermal compression
(d) Electrical heating of a nichrome wire
Option c – Isothermal compression
In all natural processes, the entropy of the universe
(a) remains constant
(b) always decreases
(c) always increases
(d) may increase or decrease
Option c – always increases
Which of the following combinations of properties would be most desirable for a cooking pot?
(a) High specific heat and low conductivity
(b) Low specific heat and high conductivity
(c) High specific heat and high conductivity
(d) Low specific heat and low conductivity
Option b – Low specific heat and high conductivity
The temperature at the bottom of a high waterfall is higher than that at the top because
(a) by itself, heat flows from higher to lower temperatures
(b) the difference in height causes a difference in pressure
(c) thermal energy is transformed into mechanical energy
(d) mechanical energy is transformed into thermal energy.
Option d – mechanical energy is transformed into thermal energy
The sprinkling of water slightly reduces the temperature of a closed room because
(a) the temperature of the water is less than that of the room
(b) the specific heat of water is high
(c) water has a large latent heat of vaporization
(d) water is a bad conductor of heat
Option c – water has a large latent heat of vaporization
The temperature of stars is determined by
(a) Stefan’s law
(b) Wien’s displacement law
(c) Kirchhoff’s law
(d) Ohm’s law
Option b – Wien’s displacement law
The fastest mode of transfer of heat is
(a) conduction
(b) convection
(c) radiation
(d) None of these
Option c – radiation
The coefficient of thermal conductivity depends upon
(a) the temperature difference between the two surfaces
(b) area of the plate
(c) material of the plate
(d) All of these
Option c – material of the plate
Good absorbers of heat are
(a) poor emitters
(b) non-emitters
(c) good emitters
(d) highly polished
Option c – good emitters
Which of the following is not close to a black body?
(a) Blackboard paint
(b) Green leaves
(c) Black holes
(d) Red roses
Option a – Blackboard paint
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