Q: Air is filled at 60°C in a vessel of open mouth. The vessel is heated to a temperature T so that 1/4th part of air escapes. Assuming the volume of vessel remaining constant, the value of T is

(a) 80°C

(b) 444°C

(c) 333°C

(d) 171°C

Ans: (d)

Sol:

PV = nRT

PV =( m/M )RT

Open mouth means pressure is constant

Hence,

$ T \propto \frac{1}{m}$

$ \frac{T_1}{T_2} = \frac{m_2}{m_1} $

m_{2}= 3m_{1}/4

and , T1 = 60+273= 333K