Thermodynamics Free Mock test 1

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ssc je, vizag steel,nlc

1. The number of degrees of freedom for a diatomic molecule

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2. Which one of the following is the extensive property of a thermodynamic system?

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Volume

Pressure

Temperature

Density

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3. During a constant pressure expansion of a gas, 33.3% heat is converted into work while the temperature rises by 20 K. The specific heat of the gas at constant pressure as a proportion of work, W is

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10%

12%

15%

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4. A fluid flowing along a pipeline undergoes a throttling process from 10 bar to 1 bar is passing through a partially open valve. Before throttling, the specific volume of the fluid is 0.5 m^3/kg and after throttling is 2.0 m^3/kg.What is the change in specific internal energy during the throttling process?

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zero

200 kJ/kg

100 kJ/kg

300 kJ/kg

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5. Joule – Thomson coefficient is the slope of

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constant enthalpy lines on T-s diagram

inversion curve on T-p diagram

inversion curve on T-s diagram

constant enthalpy lines on T-p diagram

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6. A gas is following through an insulated nozzle. If the inlet velocity of gas is negligible and there is an enthalpy drop of 45 kJ/kg, the velocity of gas leaving the nozzle is?

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100 m/s

300m/s

350 m/s

200 m/s

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7. A heat pump working on a reversed Carnot cycle has a C.O.P. of 5. If it works like a refrigerator taking 1 kW of work input, the refrigerating effect will be

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1 kW

2 kW

3 kW

4 kW

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8. A reversible engine operates between temperatures 900 K and T2 (T2<900K), and another reversible engine between T2 and 400 K (T2>400 K) in series. What is the value of T2 if work outputs of both engines are equal?

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600 K

625 K

650 K

675 K

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9. A Carnot engine operates between 37°C and 347°C. If the engine produces 620 kJ of work, the entropy change during heat addition is

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1 kJ/K

2 kJ/K

3 kJ/K

4 kJ/K

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10. During a thermodynamic process, 100 kJ of heat is transferred from a reservoir at 800 K to a sink at 400 K. The ambient temperature is 300 K. The loss of available energy is

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27.5 kJ

32.5 kJ

37.5 kJ

62.5 kJ

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11. An ideal gas is flowing through an insulated pipe at a rate of 3.3 kg. There is a pressure drop of 15% from the inlet to the outlet of the pipe. What is the rate of energy loss (in kW) because of this pressure drop due to friction, given that Rgas = 0.287 kJ/kg K and the reference temperature To is 300 K?

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42.62

38.14

40.26

35.13

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12. For a pure substance, what are the number of the thermodynamic degrees of freedom for saturated vapour and superheated vapour, respectively?

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1 and 1

1 and 2

2 and 1

2 and 2

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13. The specific volume of water when heated from 0°C

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First increases and then decreases

first decreases and then increases

increases steadily

descreases steadily

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14. For the same maximum pressure and temperature

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Otto cycle is more efficient than diesel cycle

Diesel cycle is more efficient than Otto cycle

Dual cycle is more efficient than Otto and diesel cycles

Dual cycle is less efficient than Otto diesel cycles.

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15. Which cycle consists of two reversible isotherms and two reversible isobars?

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Carnot cycle

Stirling cycle

Ericsson cycle

Brayton cycle

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16. An Otto cycle has a compression ratio of 8. If 250 kJ of work is extracted from the cycle, the heat rejected by the cycle is

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500 kJ

442.69 kJ

331.4 kJ

192.69 kJ

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17. For same power output and same compression ratio, as compared to two-stroke engines, four-stroke S.I engines have:

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higher fuel consumption

lower thermal efficiency

higher exhaust temperatures

higher thermal efficiency

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18. The reheat cycle in a steam power plant is mainly adopted to

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Improve thermal efficiency

Decrease the moisture content in low pressure stages to a safe value

Decrease capacity of condenser

Recover the waste heat of boiler

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19. A gas turbine works on which one of the following cycles?

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Otto

Brayton

Rankine

Stirling

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20. Brayton cycle with infinite inter cooling and reheat stages would approximate a

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Stirling cycle

Ericsson cycle

Otto cycle

Atkinson Cycle

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21. The maximum net specific work obtainable in an ideal Brayton cycle for Tmax = 900 K and Tmin = 400 K is given by

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100 Cp

500 Cp

700 Cp

800 Cp

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22. The most common type of absorption system in use in industrial applications is based on the refrigerant-absorbent combination of

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Air-Water

Lithium Bromide-air

Carbon dioxide-water

Ammonia-water

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23. In a VCR plant, the refrigerant leaves the compressor and evaporator with the enthalpy of 205 kJ/kg and 177 kJ/kg respectively. Enthalpy of the refrigerant leaving the condenser is 105 kJ/kg. If the mass flow rate of the refrigerant is 0.2kg/s, the refrigeration effect will be

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12.2 kW

16.4 kW

14.4 kW

20.2 kW

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24. At 100% relative humidity, the wet-bulb temperature is

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more than dew point temperature

same as dew point temperature

less than dew point temperature

equal to ambient temperature

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25. A certain air has DBT of 35°C and DPT of 20°C, the corresponding saturation pressure, of water being 5.628 kPa and 2,33 kPa respectively. When the atmospheric pressure is assumed as 1.0132 bar, the specific humidity of air will be

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2.5 * 10^(-3)

7.8 * 10^(-3)

14.7*10^(-3)

25*10^(-3)

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