A student forgot to add the reaction mixture to the round bottomed open flask at `27^(@) C` and put it on the flame After a lapse of time he realized his mistake using a pyrometer he found the temperature of the flask was `477^(@)C` What fraction of air would have been expelled out ? .

Explanation

Suppose volume of vessel =V `cm^(3)`, i.e., volume of air in the flask at `27^(@)C=V cm^(3)`.
`(V_(1))/(T_(1))=(V_(2))/(T_(2))," "i.e.," "(v)/(300)=(V_(2))/(750)" or "V_(2)=2.5" V"`
`:. " " "Volume expelled"=2.5" V"-V=1.5" V"`
`:. " " "Fraction of air expelled" `=(1.5" V")/(2.5" V")=(3)/(5)`