# Mechanical Engineering MCQs [Set 2]

11. Multistage centrifugal pumps are used to obtain
(a) high discharge
(c) pumping of viscous fluids
(d) high head and high discharge
(e) high efficiency.

12. When a piping system is made up primarily of friction head and very little of vertical lift, then pump characteristics should be
(a) horizontal
(b) nearly horizontal
(c) steep
(d) first rise and then fall
(e) none of the above.

13. In a single casing, multistage pump running at constant speed, the capacity rating is to be slightly lowered. It can be done by
(a) designing new impeller
(b) trimming the impeller size to the required size by machining
(c) not possible
(d) some other alterations in the impeller
(e) none of the above.

14. If a pump is handling water and is discharging a certain flow Q at a constant total dynamic head requiring a definite B.H.P., the same pump when handling a liquid of specific gravity 0.75 and viscosity nearly same as of water would discharge
(a) same quantity of liquid
(b) 0.75 Q
(c) Q/0.75
(d) 1.5 Q
(e) none of the above.

15. The horse power required in above case will be
(a) same
(b) 0.75 B.H.P.
(c) B.H.P./0.75
(d) 1.5 B.H.P.
(e) none of the above.

16. Low specific speed of a pump implies it is
(a) centrifugal pump
(b) mixed flow pump
(c) axial flow pump
(d) any one of the above
(e) none of the above.

17. The optimum value of vane exit angle for a centrifugal pump impeller is
(a) 10-15°
(b) 20-25°
(c) 30-40°
(d) 50-60°
(e) 80-90°.

18. In a centrifugal pump, the liquid enters the pump
(a) at the top
(b) at the bottom
(c) at the center
(d) from sides
(e) none of the above.

19. For small discharge at high pressure, following pump is preferred
(a) centrifugal
(b) axial flow
(c) mixed flow
(d) propeller
(e) reciprocating.

20. In centrifugal pumps, maximum efficiency is obtained when the blades are
(a) straight
(b) bent forward
(c) bent backward