An open vessel at `27^(@)C` is heated until `3//5^(th)` of the air in its has been expelled. Assuming that the volume of the vessel remains constant find
the air escaped out if vessel is heated to 900K.

Explanation

One should clearly note the fact that on heating a gas in a vessel, there are the number of moles of gas which go out, the volume remains constant. Let initial no. of moles of gas at 300K be 'n'. On heating `3//5` moles of air escape out at temperature T.
`:.` Moles of air left at temperature.
`T= ( n - ( 3)/( 5)n ) = ( 2n )/( 5) `
On heating vessel to 900K, let `n_(1)` moles be left, `n_(1) T_(1) = n_(2) T_(2)`
`rArr n_(1) xx 900 = 300 xxn rArr n_(1) = ( 1)/( 3)n `
`:.` moles escaped out `= n - ( n )/( 3) = ( 2)/( 3) n `moles.