Question # 1

A process which can be retraced in exactly reverse order, without producing any change in the surroundings is called

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reversible process

irreversible process

any one of them

none of them

The highest efficiency of a heat engine whose low temperature is 17°C and the high temperature is 200°C is

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70%

100%

35%

38%

Average KE of a gas molecule has:

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Direct relation with absolute temperature and inverse relation with pressure

Direction relation with both absolute temperature and pressure

Inverse relation with both absolute temperature and pressure

None of these

A diatomic gas molecule has

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translational energy

rotaional energy

vibrational energy

all of them

If denotes the total number of molecules in cubic vessel such that m is mass of each milecule and I is length of each side of vessel, then mN/I³gives the:

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Force

Density

Work done

Pressure

If a system undergoes a natural process it will go in the direction that causes the entropy of the system plus the environment to increase, this is another statement of

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second law thermodynamics

first law of thermodynamics

third law of thermodynamics

none of them

In the reverse process, the working substance passes through the same stages as in the direct process and

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thermal effects at each stage are exactly reversed

mechanical effects at each stage are exactly reversed

thermal and mechanical effects at each stage remain the same

thermal and mechanical effects at each stage are exactly reversed

At absolute temperature, the kinetic energy of the molecules

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Becomes zero

Becomes maximum

Becomes minimum

Remain constant

If a liquid is heated in weightlessness, the heat is transmitted through

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Conduction

Convection

Radiation

Neither, because the liquid cannot be heated in weightlessness

A gas which strictly obeys the gas laws under all conditions of temperature and pressure is called:

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Ideal gas

Inert gas

Real gas

None of these

The coefficient of linear expansion of iron is 0.000011 per°K. An iron rod is 10 metre long at 27°C. The length of the rod will be decreased by 1.1 mm when the temperature of the rod changes to

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0°C

10°C

17°C

20°C

Which of the following does not have the same units:

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Work

Heat

Kinetic energy

Power

If an amount of heat enters the system it could

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decrease the internal energy

not change the internal energy

increase the internal energy

none of them

Heat travels through vacuum by

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Conduction

Convection

Radiation

Both A and B

An irreversible heat flow from a hot to cold substances of a system, causes the disorder to

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decrease

remains the same

increase

any one of them

Since the absolute scale is independent of the property of the working substance, hence, can be applied at

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very high temperature

very low temperature

any one of them

none of them

The example of irreversible process is

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slowly liquification

slowly evaporation

an explosion

all of them

The volume of given mass of a gas will be doubled at atmosphere pressure if the temperature of the gas is changed from 150°C to

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300°C

573°C

600°C

743°C

For the working of a heat engine, there must be

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a source of heat at high temperature

a sink at low temperature

both of them

none of them

A carnot cycle consists of

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One step

two step

three steps

four steps

The internal energy of a system does not depend upon the

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initial state of the system

final state of the system

path

none of them

If R is gas constant for 1 gram mole, C_pand C_vare specific heat for a solid then

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C_p- C_v= R

C_p- C_{v < R}

C_p- C_{v = 0}

C_p- C_{v > R}

The efficiency of diesel engine is

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25%

25 - 30%

35%

35 - 40%

On the power stroke, a spark fires the mixtures causing a rapid increase in pressure and temperature and the burning mixture expands

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adiabatically

isothermally

isochorically

isobarically

The heat required to raise the temperature of one mole of the gas through 1 K at constant volume is called

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heat capacity

specific heat capacity

molar specific heat

molar specific heat at constant volume

At constant temperature, on increasing the pressure of a gas by 5%, its volume. The final temperature of the gas will be

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81 K

355 K

627 K

627°C

The curve representing an adiabatic process is called

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isotherm

adiabat

adiable

none of them

If the volume of the gas is to be increased by 4 times, then

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Temperature and pressure must be doubled

At constant P the temperature must be increased by 4 times

At constant T the pressure must be increased by four times

It cannot be increased

At constant volume temperature is increased. Then

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Collision on walls will be less

Number of collisions per unit time will increase

Collision will be in straight lines

Collision will not change

The curve representing an isothermal process is called

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adiabat

isotherm

fixed temperature

none of them

When the temperature of source and sink of a heat engine become equal entropy change will be

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Zero

Max

Min

-ve

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