Using data from the graph above, identify which gas, A or B, undergoes the isothermal expansion.

Using the graph opposite, estimate the difference in work done by each gas.

Explain, with reference to the first law of thermodynamics, and without further calculation, the change in temperature of the gas undergoing the adiabatic change.

choice of two data points;
to show P×V constant for gas A / not constant for gas B;

identifies area between lines as work done;
counts squares (14 squares);
each square 12.5;
175 J; (allow answers in the range of 150 to 200 J)

Q=ΔU+W and Q=0; (both needed)
so ΔU+W=0;
work done by gas is positive;
so ΔU decreases therefore temperature decreases;