An ideal gas is initially at temperature T and volume V. Its volume is increased by ∆V due to an increase in temperature ∆T, pressure remaining constant. The quantity δ = ∆V/(V ∆T) varies with temperature as

From ideal gas equation, pV = RT                                 …(i)or                  p∆V = R∆T                                             …(ii)On dividing Eq. (ii) by Eq. (i), we get                        ΔVV=ΔTT⇒ΔVVΔT=1T=δ           (Given)∴                   δ = 1TSo, the graph between δ and T will be rectangular hyperbola.