$1-$ Solve the problem $(5-19)$ from your textbook by using the gas constant for air is $R=0\mathrm{.}297$kPa.$\frac{m^3}{k}g.K,$ and the constant pressure specific heat of air at room temperature is $cp=1\mathrm{.}005k\frac{J}{k}g.$C$,$ and the outdoor air is $15$ C instead of $5$ C $.$

$2-$ Solve the problem $(5-28)$ from your textbook by using the specific heat of air $cp=1\mathrm{.}007k\frac{J}{k}g.K,$ and using the exit state of $220$ kPa instead of $200$ kPa $.$

$3-$ Solve the problem $(5-50)$ from your textbook by using the constant pressure specific heat of helium is $cp=5\mathrm{.}1926k\frac{J}{k}g*K,$ and using the inlet and outlet temperatures of $250$ K and $500$ K $,$ respectively.