$($This problem is related with compressible flows.$)$

$2-$ Air is stored in a tank of volume V and initial stagnation pressure of p$\_(01)$ and initial stagnation temperature of T$\_(0).$ The gas is discharged through a converging$-$diverging nozzle of exit$-$to$-$throat area ratio $2\mathrm{.}75.$ The throat area is A$^(*).$

a$-)$ Develop your own original expression for the mass flow rate for chocked flow as a function of tank stagnation conditions

b$-)$ If the discharge process is isothermal and choked develop an expression for the time required for the tank pressure to drop to p$.$