Steam Boilers, Engines, Nozzles and Turbines - Mechanical Engineering Multiple choice questions and Answers for Compitative exams

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
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