An ideal monatomic gas is confined in a cylinder by a spring-loaded massless piston of cross-section $8\times {10}^{-3} {\mathrm{m}}^2$. The piston can slide on the walls of the cylinder without any friction. Initially, the gas is at $300 \mathrm{K}$ and occupies a volume of $2.4\times {10}^{-3} {\mathrm{m}}^3$ and the spring is in its relaxed position. Now, gas is slowly heated by a small electric heater and the piston moves out slowly by $0.1 \mathrm{m}$. Calculate the final temperature of the gas and the heat supplied by the heater. The force constant of the spring is $8000 \mathrm{N}/\mathrm{m}$ and atmospheric pressure is $1\times {10}^{5 }\mathrm{N}/{\mathrm{m}}^2$.