##### Q11. The volumetric efficiency of a compressor, for the same compression ratio, will increase if the index of compression (n) is

(a) increased
(b) decreased
(c) constant
(d) none of the above.

Ans:(d) none of the above.

##### Q12. For the least work to be done on a compressor, the compression should be

(b) isothermal
(c) polytropic
(d) none of the above.

Ans:(b) isothermal

##### Q13. For a two-stage compressor, for maximum efficiency the condition is that the intermediate pressure should be

(a) average of the initial and final pressure
(b) geometric mean of initial and final pressure
(c) product of two pressures
(d) the ratio of two pressures.

Ans:(b) geometric mean of initial and final pressure

##### Q14. For a two-stage compressor, the ratio of diameters of L.P. cylinder to H.P. cylinder is equal to

(a) square of the ratio of final pressure to initial pressure
(b) the ratio of final pressure to initial pressure
(c) the square root of the ratio of final pressure to initial pressure
(d) cube root of the ratio of final pressure to initial pressure.

Ans:(c) the square root of the ratio of final pressure to initial pressure

##### Q15. For a three-stage compressor for maximum efficiency, the compression ratio is equal to

(a) square of the ratio of final pressure to initial pressure
(b) the ratio of final pressure to initial pressure
(c) square root of the ratio of final pressure to initial pressure
(d) cube root of the ratio of final pressure to initial pressure.

Ans:(d) cube root of the ratio of final pressure to initial pressure.

##### Q16. The phenomenon of unsteady, periodic and reversed flow is known as

(a) choking
(b) surging
(c) stalling
(d) none of the above.

Ans:(b) surging

##### Q17. The phenomenon of fixed mass flow rate in compressor regardless of pressure ratio is known as

(a) choking
(b) surging
(c) stalling
(d) none of the above.

Ans:(a) choking

##### Q18. The phenomenon of air steam not able to follow the blade contour of an axial compressor is known as

(a) choking
(b) surging
(c) stalling
(d) none of the above.

Ans:(c) stalling

##### Q19. In multi-stage compressors, the air after compression in the first stage is cooled in an intercooler at constant pressure before passing into the second stage. The cooling is said to be perfect if

(a) air is cooled to a temperature more than its original temperature
(b) air is cooled to a temperature less than its original temperature
(c) air is cooled to its original temperature
(d) none of the above.

Ans:(c) air is cooled to its original temperature

##### Q20. The assumptions made for calculating the work done in multi-stage compressor are

(a) the index of compression is same in each stage
(b) intercooling in each stage is at constant pressure
(c) suction and delivery pressures remain constant during each stage
(d) all of the above

Ans:(d) all of the above

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