# Thermodynamics (71-80)

71.

In which case the work done per kg of air compressed from 1.05 ata, 15?C to 6.3 ata is minimum

 A. Adiabatic B. Isothermal C. Polytropic pv1.3 = C D. Polytropic pv1.35 = C E. Polytropic pv1.4 = C

Explanation:

72.

In which case the heat transferred from the air when compressed from 1.05 ata 15?C to 6.3 ata would be minimum?

 A. Adiabatic B. Isothermal C. Polytropic pv1.3 = C D. Polytropic pv1.31 = C E. Polytropic pv1.35 = C

Explanation:

73.

In which case the heat transferred from the air when compressed from 1 ata 15?C to 6 ata would be maximum

 A. Adiabatic B. Isothermal C. Polytropic pv1.3 = C D. Polytropic pv1.31 = C E. Polytropic pv1.35 = C

Explanation:

74.

The value of characteristic gas constant in kg metre per kg per deg C as

 A. 96 B. 53.3 C. 29.97 D. 1554 E. 848

Explanation:

75.

The molecular volume of all the gases at 2 ata and 30?C is

 A. 1.0 cm-m B. 1.562 cu-m C. 8.48 cu-m D. 12.847 cu-m E. 25.794 cu-m

Explanation:

76.

The value of characteristic gas constant for carbon dioxide would be

 A. 29.2 kg/metre/kg/?K B. 30.4 kg/metre/kg/?K C. 19.28 kg/metre/kg/?K D. 16.1 kg/metre/kg/?K E. 10.0 kg/metre/kg/?K

Explanation:

77.

If the two specific heats of a gas are 0.237 and 0.169 respectively, the volume of 3 kg of air at 27?C under a pressure of 3 ata would be

 A. 0.204 cu-m B. 1 cu-m C. 1.5 cu-m D. 1.74 cu-m E. 2.5 cu-m

Explanation:

78.

The weight of 1 cu-m of carbon dioxide at NTP if the characteristic gas constant is 19.28 kg metre/kg/?C, would be

 A. 1 kg B. 1.5 kg C. 1.962 kg D. 2.5 kg E. 3.924 kg

Explanation:

79.

1 cu-m of steam having dryness franction 0.85 at 12 ata mixes with 1.5 kg of water at 12?C at constant pressure. The dryness fraction of resulting steam would be

 A. 0.85 B. 0.75 C. 0.637 D. 0.6 E. 0.5

Explanation:

80.

A Carnot refrigerator extracts 100 kcal of heat per minute from a cold room which is maintained at – 15?C and it is discharged to atmosphere at 30?C. The horse power required to run the unit would be

 A. 1 B. 1.5 to 2 C. 2 to 5 D. 5 to 6 E. Mone than 6