Answer: The gas would occupy volume of 221 ml at STP
Step-by-step explanation:
Combined gas law is the combination of Boyle's law, Charles's law and Gay-Lussac's law.
The combined gas equation is,

where,
= initial pressure of gas = 720 torr
= final pressure of gas = 760 torr (at STP)
= initial volume of gas = 250 ml
= final volume of gas = ?
= initial temperature of gas =

= final temperature of gas =
(at STP)
Now put all the given values in the above equation, we get:


The gas would occupy volume of 221 ml at STP