6. A hot air balloon holds 7.40 x 10 liters of gas. In order for the hot air balloon to rise into the sky, it must
be heated to 120°C. Once the balloon is up in the air, the air needs to be cooled in order for the balloon
to land. If the temperature of the balloon is decreased to 40.0°C. what will the new volume of the gas
be?

I need help idk how to do this

I) a gas contained within a piston-cylinder assembly undergoes two processes, a and b, between the same end states, 1 and 2, where p1 = 10 bar, v1 = 0.1 m3 , u1 = 400 kj and p2 = 1 bar, v2 = 1.0 m3 , u2 = 200 kj: ' process a: process from 1 to 2 during which the pressure-volume relation is pv = constant. ' process b: constant-volume process from state 1 to a pressure of 2 bar, followed by a linear pressure-volume process to state 2. kinetic and potential energy effects can be ignored. for each of the processes a and b, a) sketch the process on a p-v diagram. b) evaluate the work, in kj. c) evaluate the heat transfer, in kj.(ans : qb,12 = -65.0 kj)