Sir, An ideal gas is taken from state 1 to state 2. How does the volume change? The P-T diagram is as shown. I solved it in the following way: From the diagram it is clear that P/T is a constant. From ideal gas equation, PV = nRT V = (nR)/(P/T) = constant But the answer given in my book is that volume increases. I think the book answer is wrong. What do you say Sir?