1. For water, at pressures below atmospheric
(a) melting point rises slightly and boiling point drops markedly
(b) melting point rises markedly and boiling point drops markedly
(c) melting point drops slightly and boiling point drops markedly
(d) melting point drops slightly and boiling point drops slightly
(e) none of the above.
Ans: a
2. At very low temperature, the melting and boiling temperatures become equal. This temperature is
(a) 373°K
(b) 273.16°K
(c) 303°K
(d) 0°K.
(e) 300°K.
Ans: b
3. The critical pressure at which latent heat of vaporization is zero is
(a) 225.65 kgf/cm2
(b) 273 kgf/cm2
(c) 100 kgf/cm2
(d) 1 kgf/cm2
(e) – 1 kgf/cm2.
Ans: a
4. The latent heat of steam at pressures greater than atmospheric in comparison to latent heat at atmospheric pressure is
(a) less
(b) more
(c) equal
(d) may be less or more depending on temperature
(e) unpredictable
Ans: a
5. The saturation temperature of steam with increase in pressure increases
(a) linearly
(b) rapidly first and then slowly
(c) slowly first and then rapidly
(d) inversely
(e) none of the above.
Ans: b
6. Carbonisation of coal is the process of
(a) pulverising coal in inert atmosphere
(b) heating wood in a limited supply of air at temperatures below 300°C
(c) strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
(d) binding the pulverised coal into brickettes
(e) enriching carbon in the coal.
Ans: c
7. Coke is produced by
(a) pulverising coal in inert atmosphere
(b) heating wood in a limited supply of air at temperatures below 300GC
(c) strongly heating coal continuously for about 48 hours in the absence of air in a closed vessel
(d) binding the pulverised coal into bricketts
(e) enriching carbon in the coal.
Ans: c
8. Heating of dry steam above saturation temperature is known as
(a) enthalpy
(b) superheating
(c) supersaturation
(d) latent heat
(e) super tempering.
Ans: b
9. Superheating of steam is done at
(a) constant volume
(b) constant temperature
(c) constant pressure
(d) constant entropy
(e) constant enthaply.
Ans: c
10. 1 kg.m is equal to
(a) 9.81 Joules
(b) All Joules
(c) 427 Joules
(d) 102 Joules
(e) 539 Joules.
Ans: a
11. If partial pressure of air and steam be pa and ps respectively in a condenser, then according to Dalton’s law, the pressure in condenser is equal to
(a) Ps-Pa
(b) pa-ps
(C) Pa+P,
Ans: c
12. Equivalent evaporation is the amount of water evaporated in a boiler from and at
(a) 0°C
(b) 100°C
(c) saturation temperature at given pres¬sure
(d) room temperature
(e) 20°C.
Ans: b
13. The specific volume of steam with increase in pressure decreases
(a) linearly
(b) slowly first and then rapidly
(c) rapidly first and then slowly
(d) inversely
(e) none of the above.
Ans: c
14. The equivalent evaporation of a boiler is a measure to compare
(a) the given boiler with the model
(b) the two different boilers of the same make
(c) two different makes of boilers operating under the same operating conditions
(d) two boilers of same make but operating under different conditions
(e) any type of boilers operating under any conditions.
Ans: e
15. The coal requirement per kW hour generation in the thermal power plant is of the order of
(a) 0.1 to 0.2 kg
(b) 0.2 to 0.4 kg
(c) 0.6 to 0.8 kg
(d) 1.0 to 1.5 kg
(e) 1.5 to 2 kg.
Ans: c
16. Sublimation region is the region where
(a) solid and vapour phases are in equilibrium
(b) solid and liquid phases are in equilibrium
(c) liquid and vapour phases are in equilibrium
(d) solid, liquid and vapour phases are in equilibrium
(e) none of the above.
Ans: a
17. Stoichiometric quantity of air is the
(a) air present in atmosphere at NTP conditions
(b) air required for complete combustion of fuel with no excess air
(c) air required for optimum combustion so as to have reasonable excess air
(d) air required to convert CO into C02
(e) air required to form an explosive mixture.
Ans: b
18. One kg of steam sample contains 0.8 kg dry steam; it’s dryness fraction is
(a) 0.2
(b) 0.8
(c) 1.0
(d) 0.6
(e) 0.5
Ans: b
19. If a steam sample is nearly in dry condition, then its dryness fraction can be most accurately determined by
(a) throttling calorimeter
(b) separating calorimeter
(c) combined separating and throttling calorimeter
(d) bucket calorimeter
(e) none of the above
Ans: a
20. If xx and x2 be the dryess fractions obtained in separating calorimeter and throttling calorimeter respectively, then the actual dryness fraction of steam will be
(a) xxx2
(b) x, + x2
Ans: a
21. The specific heat of superheated steam in kcal/kg is generally of the order of
(a) 0.1
(b) 0.3
(c) 0.5
(d) 0.8
(e) 1.0
Ans: c
22. On Mollier chart, flow through turbine is represented by
(a) horizontal straight line
(b) vertical straight line
(c) straight inclined line
(d) curved line
(e) none of the above.
Ans: b
23. A wet vapour can be completely specified by
(a) pressure only
(b) temperature only
(c) dryness fraction only
(d) specific volume only
(e) pressure and dryness fraction.
Ans: e
24. On Millier chart, the constant pressure lines
(a) diverge from left to right
(b) diverge from right to left
(c) are equally spaced throughout
(d) first rise up and then fall
(e) none of the above.
Ans: a
25. On Mollier chart, free expansion, or throttling process from high pressure to atmosphere is represented by
(a) horizontal straight line
(b) vertical straight line
(c) straight inclined line
(d) curved line
(e) none of the above.
Ans: a