Air enters a turbine operating at steady state at 6 bar and $1100 \mathrm{~K}$ and expands isentropically to a state where the temperature is $700 \mathrm{~K}$. Employing the ideal gas model and ignoring kinetic and potential energy changes, determine the pressure at the exit, in bar, and the work, in $\mathrm{kJ}$ per $\mathrm{kg}$ of air flowing, using
(a) data from Table A-22.
(b) $I T$.
(c) a constant specific heat ratio from Table A-20 at the mean temperature, $900 \mathrm{~K}$.
(d) a constant specific heat ratio from Table A-20 at $300 \mathrm{~K}$.