Question

to increase volume of gas by 10% how much should pressure be decreased

Answer 1

PV = P'V'
PV = P'(V + 10V/100) = P' 1.1V
P'= P/1.1 = 0.9P

So, pressure should be decreased by 10% in order to increase volume by 10%.

Answer 2

Calculate it by using udeal gas equation

P V = nRT
where
R*T = 22.4L
P = pressure
V= volume