Answer :
Area of stopper = π * 0.011^2
Force pushing DOWN on top = 1.013 * 10^5 * π * 0.011^2 = 38.507 N
15.0 = Force up – 38.507
Force up = 15.0 + 38.507 = 53.507 N
Pressure on inside surface of stopper = Force up Ă· area
Pressure = 53.507 Ă· (Ď€ * 0.011^2) = 1.4076 * 10^5
Initial Temperature = 18 + 273 = 291°K
1.013 * 10^5 / 1.4076 * 10^5 = 291 / T
T = 404°K – 273 = 131°C