Question

On a p-v plane for a pure substance in superheated region, the slopes of constant temperature lines are
positive
negative
zero
infinite

Answer 1

On a p-v plane for a pure substance in superheated region, the slopes of constant temperature lines are – Negative

 

In a superheated condition, a pure substance tends to act like an Ideal gas.  

 

According to Boyle’s law, PV = Constant.

 

Therefore, the isothermal lines are hyperbolic. As the volume decreases, the slope steepens and as the volume increases, it is less steep. Therefore, the slope of an isothermal line in the superheated region will be negative.