work done in first stage should be more
work done in subsequent stages should increase
work done in subsequent stages should decrease
work done in any stage is no criterion for minimum work but depends on other factors.

increase velocity
make the flow stream-line
convert pressure energy into kinetic energy
increase degree of reaction.

compressor efficiency
isentropic efficiency
Euler's efficiency
pressure ratio.

same as isothermal
same as adiabatic
better than isothermal and adiabatic
none of the above.

air stream blocking the passage
motion of air at sonic velocity
unsteady periodic and reversed flow
production of no air pressure.

centrifugal compressors deliver prac-tically constant pressure over a con-> siderable range of capacities
Axial flow compressors have a sub-stantially constant delivery at variable pressures
centrifugal compressors have a wider stable operating range than axial flow compressors
axial flow compressors apt to be longer as compared to centrifugal type.