A cylinder of ideal gas is closed by an 8 kg movable piston of area 60 cm2 . The atmospheric pressure is 100 kPa. When the gas is heated from 30∘C to 100∘C , the piston rises 20 cm. The piston is then fastened in the place and the gas is cooled back to 30∘C . If ΔQ1 is the heat added to the gas during heating and ΔQ2 is the heat lost during cooling, find the difference.