7. •• An ideal gas is under an initial pressure of 2.45 × 104 Pa and occupies a volume of 0.20 m3. The slow addition of 8.4 × 103 J of heat to this gas causes it to expand isobarically to a volume of 0.40 m3.

(a) How much work is done by the gas?

(b) Does the thermal energy of the gas change? If so, by how much?