Question # 1

Efficiency of carnot engine is independent of the

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temperature of sink

temperature of source

nature of the working substances

none of them

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

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

If 42 J heat is transferred to the system and the work done by the system is 32 J then what will be the change in internal energy

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0 J

2 J

5 J

10 J

The efficiency of petrol engine is usually not more than 25% to 30% because of

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friction

heat losses

both of them

none of them

The work done by the system on its environment is considered as

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positive

negative

zero

any one of them

Tick the correct pair when M denotes the molecular mass and other symbols carry usual meanings:

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N = nN_Am = MN_A

n = N N_A, M = mN_A

M = N_A/N , N_A= m/n

N = nN_A, M = mN_A

Specific heat at constant pressure is greater than the specific heat at constant volume because

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Heat is used up to increase temperature at constant pressure

Heat is used by gas for expansions purposes at constant pressure

Heat is use dup to increase internal energy

The above statement is invalid

The percentage of available heat energy converted into work by a diesel engine is roughly

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35 %`

40 %

35 - 40 %

25 %

Amount of heat required to raise the temperature of a body through 1 K is called its

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Specific heat

Water equivalent

Thermal capacity

Entropy

If water in a closed bottle is taken up to the moon and opened, the water gets

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Freeze

Boiled

Dissociated into O₂and H₂

Evaporated

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}

While deriving equation of pressure by kinetic theory of gases, we take into account:

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Only linear motion of molecules

Only rotational motion

Only vibratory motion

All of these

When two objects come to common temperature, the body is said to be in:

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Static equilibrium

Dynamic equilibrium

Thermal equilibrium

None of these

Pressure exerted by a gas is

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Independent of density of the gas

Inversely proportional to the density of the gas

Directly proportional to the square of the density of the gas

Directly proportional to the density of the gas

10 c.c. each of oxygen and hydrogen are kept in separate flasks. Then which of the following relations is correct?

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Each have same number of molecules

Don't have same number of molecules

Can't be predicted

None

One kilogram of different substances contain

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same number of molecules

different number of molecules

may be same or different

none of them

Rice takes longest to cook

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In a submarine 100 m below the surface of the sea

At sea level

At Murree

At Mount Everest

Truth of kinetic energy is confirmed by:

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Diffusion of gases

Brownian motion

Both A and B

None of these

The efficiency of carnot engine cannot be 100% or one unless cold reservoir is at

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100 K

273 K

0 K

-273 K

In the theory of dimensional analysis, heat may be properly represented by:

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ML²T^-2

MT^-2

ML^-1T^-1

None of these

At the constant temperature, if the value of a given mass of a gas is double, then the density of gas becomes:

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Double

Remains constant

Half

None of these

Two metal rods A and B have their initial lengths in the ratio 2 : 3 and coefficients of linear expansion in the ratio 4 : 3. When they are heated through same temperature difference the ratio of their linear expansion is

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1 : 2

2 : 3

3 : 4

8 : 9

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

In an adiabatic process the work is done at the expense of the

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energy supplied to the system

energy gained from the surroundings

internal energy

none of them

The basis to define a temperature scale that is independent of material properties is provided by

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carbon cycle

nitrogen cycle

Carnot cycle

irreversible cycle

Triple point of water is

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273.16°F

372.16K

273.16°F

273.16

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

The example of reversible process is

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an explosion

changes occur suddenly

slow compression of a gas

all of them

Hotness and coldness of an object is represented in terms:

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Heat

Temperature

Chemical energy

None of these

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