physics MCQs - 11th class Chapter 11 Mcqs

1

According to the kinetic theory, the pressure exerted by a gas is the momentum transferred to the walls of the container per second per unit ______.

A

volume

B

area

C

length

D

mass

2

The average translational kinetic energy of gas molecules is directly proportional to the ______ of the gas.

A

pressure

B

volume

C

temperature

D

mass

3

The internal energy of an ideal gas is generally the ______ of its molecules.

A

translational kinetic energy

B

vibrational energy

C

rotational energy

D

potential energy

4

Which law states that for a fixed mass of gas, pressure is inversely proportional to volume at constant temperature?

A

Charles's Law

B

Pascal's Law

C

Boyle's Law

D

Avogadro's Law

5

An isothermal process is carried out at constant ______.

A

pressure

B

volume

C

energy

D

temperature

6

In an adiabatic process, what is equal to zero?

A

Work done (W)

B

Change in internal energy (ΔU)

C

Heat transfer (Q)

D

Change in temperature (ΔT)

7

The first law of thermodynamics is a statement of the conservation of ______.

A

mass

B

charge

C

momentum

D

energy

8

For an ideal gas, the relationship between the molar specific heats at constant pressure ($C_p$) and constant volume ($C_v$) is:

A

$C_p + C_v = R$

B

$C_p - C_v = R$

C

$C_v - C_p = R$

D

$C_p / C_v = R$

9

A process that can be retraced in exactly the reverse order without any change in the surroundings is called a(n) ______ process.

A

adiabatic

B

isothermal

C

irreversible

D

reversible

10

A heat engine converts ______ energy to mechanical work.

A

chemical

B

thermal

C

nuclear

D

potential

11

The efficiency of a Carnot engine depends on the ______.

A

working substance

B

size of the engine

C

temperatures of the hot and cold reservoirs

D

pressure of the gas

12

According to the second law of thermodynamics, it is impossible for a heat engine to convert heat entirely into ______ without rejecting some heat.

A

work

B

internal energy

C

potential energy

D

sound

13

The measure of disorder in a system is called ______.

A

enthalpy

B

entropy

C

internal energy

D

work

14

The thermodynamic scale of temperature is independent of the ______.

A

pressure of the gas

B

volume of the gas

C

properties of the working substance

D

mass of the gas

15

The value of Boltzmann constant 'k' is ______.

A

$8.314 J mol^{-1} K^{-1}$

B

$1.38 x 10^{-23} J K^{-1}$

C

$6.022 x 10^{23} mol^{-1}$

D

$9.1 x 10^{-31} kg$

16

Which of the following is an example of an adiabatic process?

A

Melting of ice

B

Boiling of water

C

Rapid escape of air from a burst tyre

D

Slow compression of a gas

17

The work done by a gas during an expansion at constant pressure P is given by ______.

A

$W = P / ΔV$

B

$W = ΔV / P$

C

$W = PΔV$

D

$W = -PΔV$

18

In the equation $PV = NkT$, 'k' represents the ______.

A

Universal gas constant

B

Avogadro's number

C

Boltzmann constant

D

Stefan's constant

19

When heat Q is added to a system, it results in an increase in internal energy ΔU and work W done by the system. The correct equation is:

A

$Q = ΔU - W$

B

$W = Q + ΔU$

C

$ΔU = Q + W$

D

$Q = ΔU + W$

20

The efficiency of a petrol engine is approximately ______.

A

5% to 10%

B

25% to 30%

C

35% to 40%

D

50% to 60%

21

The efficiency of a diesel engine is approximately ______.

A

15% to 20%

B

25% to 30%

C

35% to 40%

D

60% to 70%

22

A reversible process for which the change in entropy is zero must be a(n) ______ process.

A

isothermal

B

adiabatic

C

isobaric

D

isochoric

23

The triple point of water, a standard fixed point for the thermodynamic scale of temperature, is defined to be ______.

A

0 K

B

100 K

C

273.16 K

D

373.15 K

24

In a four-stroke petrol engine, the burning mixture expands adiabatically during the ______ stroke.

A

intake

B

compression

C

power

D

exhaust

25

The change in entropy ($ΔS$) is defined by the relation ______.

A

$ΔS = T / ΔQ$

B

$ΔS = ΔQ * T$

C

$ΔS = ΔQ / T$

D

$ΔS = ΔQ + T$

26

The pressure equation derived from the kinetic theory of gases is ______.

A

$P = 1/3 ρ <v^2>$

B

$P = 1/2 ρ <v^2>$

C

$P = 2/3 ρ <v^2>$

D

$P = ρ <v^2>$

27

What happens to the internal energy of a gas during an isothermal expansion?

A

Increases

B

Decreases

C

Remains constant

D

Becomes zero

28

What happens to the temperature of a gas during an adiabatic expansion?

A

Increases

B

Decreases

C

Remains constant

D

Becomes zero

29

The work done in a P-V diagram is represented by the ______ under the curve.

A

slope

B

area

C

length

D

height

30

Human metabolism is an application of which law of thermodynamics?

A

Zeroth Law

B

First Law

C

Second Law

D

Third Law

31

The formula for the efficiency of a heat engine is ______.

A

η = 1 - (Q1 / Q2)

B

η = (Q1 - Q2) / Q2

C

η = 1 - (Q2 / Q1)

D

η = Q1 / W

32

For a Carnot engine, the ratio of heats Q2/Q1 is equal to the ratio of ______.

A

pressures P2/P1

B

volumes V2/V1

C

temperatures T2/T1

D

entropies S2/S1

33

All natural processes tend to proceed towards a state of greater ______.

A

order

B

energy

C

disorder

D

stability

34

Thermal pollution is an inevitable consequence of the ______ law of thermodynamics.

A

zeroth

B

first

C

second

D

third

35

The sum of all forms of molecular energies (kinetic and potential) of a substance is termed as its ______.

A

enthalpy

B

entropy

C

internal energy

D

heat capacity

36

The collisions between gas molecules and the walls of the container are assumed to be ______.

A

perfectly inelastic

B

partially elastic

C

perfectly elastic

D

partially inelastic

37

In an ideal gas, the molecules are considered mere mass points that exert ______ on one another.

A

gravitational forces

B

strong nuclear forces

C

no forces

D

electromagnetic forces

38

Work done on the system by the environment is conventionally taken as ______.

A

positive

B

negative

C

zero

D

infinite

39

The molar specific heat at constant pressure ($C_p$) is always ______ than the molar specific heat at constant volume ($C_v$).

A

less

B

equal

C

greater

D

double

40

A refrigerator is essentially a heat engine operating in ______.

A

a cycle

B

reverse

C

a straight line

D

parallel

41

The unit of entropy is ______.

A

Joule (J)

B

Kelvin (K)

C

Joule per Kelvin (J/K)

D

Watt (W)

42

What device in a diesel engine ignites the fuel mixture?

A

Spark plug

B

Injector

C

High temperature from compression

D

Carburetor

43

A process that occurs suddenly or involves friction is generally ______.

A

reversible

B

isothermal

C

adiabatic

D

irreversible

44

The equation $PV^γ = Constant$ is valid for which process?

A

Isothermal

B

Isobaric

C

Adiabatic

D

Isochoric

45

The value of the universal gas constant R is ______.

A

$1.38 x 10^{-23} J K^{-1}$

B

$8.314 J mol^{-1} K^{-1}$

C

$9.8 m/s^2$

D

$6.67 x 10^{-11} Nm^2/kg^2$

46

If the change in internal energy of a system is zero, as in a cyclic process, the first law of thermodynamics states that ______.

A

$Q = 0$

B

$W = 0$

C

$Q = W$

D

$Q = -W$

47

The efficiency of a real heat engine is always ______ the efficiency of a Carnot engine operating between the same temperatures.

A

greater than

B

equal to

C

less than

D

unrelated to

48

Increasing the temperature of the hot reservoir ______ the efficiency of a Carnot engine.

A

decreases

B

does not change

C

increases

D

makes it zero

49

The increase in entropy signifies a ______ of energy.

A

creation

B

degradation

C

conservation

D

purification