$(3$ points$)$

An insulated $8\mathrm{.}2m^3$ rigid tank contains air initially at $315$ K and $175$ kPa $.$ A $27$ heater running off a constant $118$ V power source is used to heat the air. The heater

is turned on long enough for the pressure to increase to $350$ kPa $.$

a$)$ How much boundary work is done?

kJ

b$)$ How long must the heater remain on $($accounting for the fact that the specific heat is not constant$)?$

minutes

c$)$ How long must the heater remain on assuming the specific heat is constant at a value taken from $300$ K $?$

minutes