Question

An open vessel at 27C is heated until three fifth of the gas has been expelled out assuming that volume of vessel remain constant the temperature of which the vessel has been heated was

Answer 1

Charles' Law (air is an ideal gas) : V1/T1 = V2/T2

Let x be the volume of the vessel. The volume of the air at the start (V1) is x. After heating, 2/5 of the air fills a volume of x. Assuming uniform expansion:
(2/5)(V2)=x => V2=(5/2)(x)=5x/2

27 Celsius = 300 Kelvin

Subbing in: x/300 = (5x/2)/T2

x cancels on both sides and solving for T2 we get: T2 = 1500/2 = 750 K = 477 C