12th Class Physics Chapter Heat MCQs:

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Sindh -> 12th Class -> Physics -> Heat

Question:

All natural process proceed in the direction of

A: increased entropy
B: decreased entropy
C: no entropy
D: none of these
Answer: A

Question:

entropy means the

A: order of a system
B: disorder of the system
C: energy available
D: none of these
Answer: B

Question:

If the temperature of the sink is decreased, efficiency of the carnots engine

A: remains unchanged
B: increased
C: decreases
D: becomes 4 times
Answer: B

Question:

Carnots engine is a ________ heat engine.

A: reversible
B: irreversible
C: ideal
D: both A and C
Answer: D

Question:

Thermal radiations are type of

A: mechanical waves
B: transverse waves
C: electromagnetic waves
D: electrons
Answer: C

Question:

In the formula PV=nRT, n represent

A: number of molecules per unit volume
B: number of moles
C: number of molecules
D: number of atoms
Answer: B

Question:

Boltzman constant is actually

A: gas constant per mole
B: gas constant per kg
C: gas constant per molecule
D: product of pressure and area
Answer: C

Question:

When a gas is compressed

A: its internal energy decreases
B: its temperature decreases
C: its temperature increases
D: nothing happens
Answer: C

Question:

Brownian motion confirms the truth of

A: wave theory of light
B: boyles law
C: kinetic theory of gases
D: adiabatic process
Answer: C

Question:

The number of molecules in one mole of a gas is called

A: avagadros number
B: boltzman constant
C: gas constant
D: none of these
Answer: A

Question:

When a substance is heated the heat energy is converted in to

A: kinetic energy
B: potential energy
C: internal energy
D: power
Answer: C

Question:

In an isothermal process, the internal energy of a system

A: increases
B: decreases
C: remains same
D: become double
Answer: C

Question:

At constant temperature, if the density of a gas is increased, its pressure will

A: decrease
B: increase
C: remain same
D: unchanged
Answer: B

Question:

In an ideal gas the molecules have only

A: potential energy
B: kinetic energy
C: both K.E and P.E
D: none of these
Answer: B

Question:

the electromagnetic waves emitted by hot bodies are called

A: photoelectrons
B: alpha rays
C: thermal radiations
D: gamma rays
Answer: C

Question:

Truth of kinetic molecular theory is confirmed by

A: diffusion of gases
B: brownian motion
C: photoelectric effect
D: both A and B
Answer: D

Question:

SI unit of heat is

A: kelvin
B: joule
C: btu
D: none of these
Answer: B

Question:

Real gases obeys gas laws at

A: high temperature and low pressure
B: high pressure and low temperature
C: high temperature and high pressure
D: does not obey gas laws at all
Answer: C

Question:

the measure of hotness or coldness of a body is called

A: internal energy
B: thermodynamics
C: temperature
D: heat
Answer: C

Question:

Total Entopy Change During any reversible cycle is

A: Zero
B: Infinite
C: Both A & B
D: None
Answer: C
Maham