If a gas undergoes an isobaric process, which of the fol-lowing statements is true?

In an isobaric process on an ideal gas, pressure is constant while the gas either expands or is compressed. Since the volume of the gas is changing, work is done either on or by the gas. Also, from the ideal gas law with pressure constant, $P\Delta V = nR\Delta T$; thus, the gas must undergo a change in temperature having the same sign as the change in volume. If $\Delta V >0$, then both $\Delta T$ and the change in the internal energy of the gas are positive $(\Delta U > 0)$. However, when $\Delta V >0$, the work done on the gas is negative $( \Delta W < 0)$, and the first law of thermodynamics says that there must be a positive transfer of energy by heat to the gas $(Q = \Delta U - W> 0)$. When $\Delta V <0$, a similar argument shows that $\Delta U <0, W >0$, and $Q = \Delta y - W < 0$. Thus, all of the other listed choices are false statements.