In an adiabatic expansion of air the volume increases by 5%. The percentage change in pressure is

We know that PVγ= constant Differentiating, we getP⋅γVγ−1dV+VγdP=0or        γdVV=−dPP            ....(1)Given   dVV×100=5 or dVV=120From eq. (1),     1⋅4×120=−dPPor    dPP×100=100×1⋅4×(1/20)=7%