Thermodynamics Set 6 MCQs

Q1 | A substance above critical temperature exists as

Solid

Liquid

Gas

Unsaturated vapour

Any of the above

Q2 | In the above problem work done is equal to

130 kcal

150 kcal

100 kcal

80 kcal

180 kcal

Q3 | In a boiler a fusible plug is located at the

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inlet to stop valve

top of superheater

bottom of drum

bottom of fire tubes

Q4 | For maximum specific output of a constant volume cycle

The working fluid should be air

The speed should be high

Suction temperature should be high

Temperature of the working fluid at the end of compression and expansion should be equal

Exhaust pressure should be high

Q5 | A frictionless heat engine can be 100% efficient only if its exhaust temperature is

Equal to its input temperature

Less than its input temperature

0?K

?100?C

0?C

Q6 | In steam tables, the entropy is shown as zero for

saturated liquid at 0?C

saturated vapours at atmospheric pressure

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saturated vapour at 0?C

saturated liquid at atmospheric pressure

Q7 | When a gas is to be stored, the type of compression that would be ideal is

Isothermal

Adiabatic

Polytropic

Constant pressure

None of the above

Q8 | Diffusion is

Mixing of two portions of fluid

Mixing of a gas in two containers at different pressures

Mixing of two portions of a fluid at different temperatures

Mixing of unlike fluids

None of the above

Q9 | In case the temperature of a hot body is increased by 50%, the amount of radiation emitted by it would increase by nearly

250%

500%

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50%

125%

Q10 | The efficiency of cycle would be

66.7 percent

100 percent

88.8 percent

37.7 percent

78.3 percent

Q11 | If the temperature of the sink is decreased, the efficiency of a Carnot engine

remain unaffected

first increased and then decreases

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decreases

increases

Q12 | When a gas is to be stored, the type of compression that would be ideal is

Isothermal

Adiabatic

Polytropic

Constant volume

None of the above

Q13 | According to Lussac's law for perfect gases, the absolute pressure of given mass varies directly as

Temperature

Absolute temperature

Absolute temperature in case the volume remains constant

The product of volume and absolute temperature

None of the above

Q14 | Gibbs free energy G is given by

G = T . H . s.

G = H/Ts

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G = H - Ts

G = H + Ts

Q15 | A sterling cycle consists of

Two isothermal and two adiabatic processes

Two constant volume and two constant pressure processes

Two adiabatic and two isentropic processes

Two isothermal and two constant volume processes

Two adiabatic and two constant pressure processes

Q16 | A reversible process requires that

Newton's law of viscosity be satisfied

There whould be no viscous or coulomb friction in the system

Heat transfer occurs from surrounding to system only

Temperature of system and surroundings be equal

There be no heat transfer

Q17 | The area of pv diagram for a Carnot cycle represents

Enthalpy drop

Volume and pressure ratios.

Temperature drop

Work done

Total heat supplied

Q18 | An adlabatic wall permits

Heat exchange by all the three modes of heat transfer

No heat exchange

Radiation heat flow only

Convective heat flow only

Conduction heat flow only

Q19 | The melting point of ice

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decreases with increase in atmospheric pressure

increases with increase in atmospheric pressure

is independent of atmospheric pressure

Q20 | In an isothermal process change in internal energy

Depends on the friction and other factors

Becomes zero

Remains constant

Decreases

Increases

Q21 | When two gases are not under the same conditions of temperature and pressure, upon mixing there will be

loss of entropy to the surroundings

exchange of entropy between the two gases

increase in available heat but decrease in unavailable heat

None of the above

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Q22 | The dew point temperature of humid air is

the temperature of air obtained on cooling it till saturation at constant volume

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always higher than the wet bulb temperature

the temperature of air obtained on cooling it till saturation at constant pressure

never lower than the wet bulb temperature

Q23 | Which one of the following is heterogeneous system

Cooking gas in a cylinder

The cooling fluid in the radiator

A mixture of hydrogen and oxygen

Atmospheric air

A mixture of ice, water and system.

Q24 | The value of characteristic gas constant for carbon dioxide would be

19.28 kg/metre/kg/?K

30.4 kg/metre/kg/?K

29.2 kg/metre/kg/?K

16.1 kg/metre/kg/?K

10.0 kg/metre/kg/?K

Q25 | In case of centrifugal compressors the phenomenon of fixed mass flow rate in compressor regardless of pressure ratio is known as

Choking

Stalling

Recirculation

Surging

Regeneration