Q. 101
A piston-cylinder device initially contains $1 \mathrm{~m}^{3}$ of air at $200 \mathrm{kPa}$ and $25^{\circ} \mathrm{C}$. Air expands at constant pressure while a heater of $250 \mathrm{~W}$ is switched on for 10 minutes. There is a heat loss of $4 \mathrm{~kJ}$ during this process. Assuming air as an ideal gas, the final temperature of air is ${ }^{\circ} \mathrm{C}$ (rounded off to one decimal place).
Use the following data for air: $\quad R=0.287 \mathrm{~kJ} / \mathrm{kg}-\mathrm{K}, c_{p}=1.005 \mathrm{~kJ} / \mathrm{kg}-\mathrm{K}$
