The correct option is C + 25 %
According to Boyle's law, we know that
PV=constant at constant temperature
∴ we can write that,
P1V1=P2V2 ..............(1)
Given,
P is decreased by 20 %
Thus,
Initial pressure (P1)=P
Final pressure (P2)=P−20100P
Initial volume (V1)=V
Final volume (V2)=V′
From (1), we can write that
PV=80100PV′
⇒V=80100V′ .......(2)
Percentage change in volume is given by,
Final volume (V′)− Initial volume (V)Initial volume (V)×100
Using (2) in the above formula, we get
V′−VV×100=100−8080×100=+25 %
Thus, option (c) is the correct answer.