31. The critical pressure ratio (p₂/p₁) is given by

32. In reaction turbines, the axial thrust is due to

A. pressure drop across the rotor
B. change in axial velocity
C. both (a) and (b)
D. none of these

33. Which of the following statement is correct?

A. The expansion of steam in a nozzle follows Rankine cycle.
B. The friction in the nozzle increases the dryness fraction of steam.
C. The pressure of steam at throat is called critical pressure.
D. all of the above

34. A binary vapor plant consists of

A. steam turbine
B. steam condenser
C. mercury boiler
D. all of these

35. In a De-Laval nozzle expanding superheated steam from 10 bar to 0.1 bar, the pressure at the minimum cross-section (i. e. pressure at throat, p₂) will be

A.3.3 bar
B.5.46 bar
C.8.2 bar
D.9.9 bar

36. The stage efficiency (η_S) is given by (where η_B = Blading efficiency and η_N = Nozzle efficiency)

A. η_S = η_B x η_N
B. η_S = η_B/η_N
C. η_S = η_N/η_B
D. none of these

37. The critical pressure ratio for initially dry saturated steam is more as compared to initially wet steam.

A. Yes
B. No

38. In a convergent-divergent nozzle, the discharge depends upon the initial conditions of steam and the area of nozzle at throat.

A. Correct
B. Incorrect

39. Parson’s reaction turbine is a __________ reaction turbine.

A. 40 percent
B. 50 percent
C. 60 percent
D. 70 percent

40. The turbine blades are

A. straight
B. circular
C. curved