Question

An open vessel at $300\, K$ is heated till $2/5^{th}$ of the air in it is expelled. Assuming that the volume of the vessel remains constant, the temperature to which the vessel is heated, is

• A. $1500\, K$
• B. $400\, K$
• C. $500\, K$
• D. $750\, K$

Answer 1

Answer: (C)

We know at constant $V$ and $P$ :
$n _{1} T _{1}= n _{2} T _{2}$
$\left[\because P_{1} V_{1}\right.$ constant $]$
$n _{1}= n$ and $n _{2}= n -\frac{2 n }{5}$ and $T _{1}=300\, K$
$n (300)=\left( n -\frac{2}{5} n \right)\left( T _{2}\right)=\left(\frac{3 n }{5}\right) T _{2}$
$T _{2}=500\, K$