Consider the following statements pertaining to isentropic flow:
1. To obtain stagnation enthalpy, the flow need not be decelerated isentropically but should be decelerated adiabatically.
2. The effect of friction in an adiabatic flow is to reduce the stagnation pressure and increase entropy
3. A constant area tube with rough surface can be used as a subsonic nozzle.
Which of these statements are correct?
(a) 1,2 and 3 (b) 1 and 2
(c) 1 and 3 (d) 2 and 3