A student forgot to add the reaction mixture to the round-bottomed flask at 27°C but put it on the f — States of Matter and Gaseous State Chemistry Question

Question

A student forgot to add the reaction mixture to the round-bottomed flask at 27°C but put it on the flame. After a lapse of time, he realized his mistake. Using a pyrometer, he found the temperature of the flask as 477°C. What fraction of air would have been expelled out?