Simple Chemical Questions
1) Lewis number, Le is given by
(a) Sc /Pr
(b) Re.Pr
(c) Sc.Pr
(d) Sh.Pr
(2) Absorption factor is defined as
(a) mGL
(b) mG/L
(c) G/mL
(d) L/mG
(3) A particle attains its terminal velocity when
(a) gravity force + drag force=buoyancy force
(b) gravity force – drag force=buoyancy force
(c) buoyancy force = gravity force
(d) drag force=buoyancy force
(4) In common fluids flowing through tubes, heat transfer by conduction is limited to the viscous sub layer. In liquid metals flowing through tubes,
(a) likewise, heat transfer by conduction is limited to the viscous sub layer
(b) heat transfer by conduction is important in the viscous sub layer as well as in the buffer layer
(c) heat transfer by conduction is important throughout the entire turbulent core
(d) Heat transfer by convection only is important; heat transfer by conduction is negligible even in the viscous sub layer
(5) Under otherwise uniform conditions Fanning friction factor for a rough pipe is
(a) smaller than that for a smooth pipe
(b) greater than that for a smooth pipe
(c) equal to that for a smooth pipe.
(6) A hot fluid at 100oC is to be cooled to 60oC in a double-pipe heat exchanger by using a coolant which will be heated from 30oC to 60oC. If the hot and cold streams flow concurrently, the driving force for heat transfer (by mean temperature difference) is equal to
(a) 0 oC
(b) 30oC
(c) 40oC
(d)none of these
(7) In SI system, net positive suction head (NPSH) has a unit of
(a) kg/ m2
(b) N/ m2
(c) J/ m
(d) J/kg
(8) Cavitation will not occur if the sum of the velocity and pressure heads at the suction is
(a) zero
(b) much larger than the vapour pressure of the liquid
(c) much smaller than the vapour pressure of the liquid
(d) Equal to the vapour pressure of the liquid.
Source: Nandi Group