The pressure of a given mass of a gas changes from 200Nm-2 to 120Nm-2 while the temperature drops from 127°C to -73°C. The ratio of the final volume to the initial volume is
A. 2 : 5 B. 5 : 4 C. 5 : 2 D. 4 : 5
Correct Answer: B
Explanation
P1 = 300Nm-2; P2 = 120Nm-2 T1 = 127 + 273; T2 = -73 + 273 = 400K; = 200K Let the initial volume V1; and the final volume = V2 ∴ P1V1/T1 = P2V2/T2 P1V1T2 = P2V2T1 ∴ V2/V1 = P1T2/P2T1 ∴ V2/V1 = (300 x 200)/(120 x 400) = 5/4 ∴ V2 : V1 = 5 : 4
