In adiabatic flow with friction, the stagnation temperature along a streamline ____________ (increase / remains constant)

Consider a Rankine cycle with superheat. If the maximum pressure in the cycle is increased without changing the maximum temperature and the minimum pressure, the dryness fraction of stream after the isentropic expansion will increase / decrease _____________

For a given set of operating pressure limits of a Rankine cycle, the highest efficiency occurs for

For a single stage impulse turbine with rotor diameter of $$2$$ $$m$$ and a speed of $$3000$$ $$rpm$$ when the nozzle angle is $${20^0},$$ the optimum velocity of steam in $$m/s$$