Question

on a p-v plane for a pure substance in superheated region,the slope of constant temperature line are?

Answer 1

For constant temperature line it is negative and for other processes it could be anything from zero to infinity but never positive cause pressure and volume never increase simultaneously. And the value of slope depends on the nature of the process. In superheated condition pure substance act like an Ideal gas. When volume decreases slope become steeper and it higher volumes it's less.