Explanation:
Since methane gas is at 1 atm and 273 K, it is at standard temperature and pressure(STP).
One mole of every gas occupies 22.4 dm^3 at STP, and vice versa. So,
22.4 dm^3 at STP of CH4=1 mol=12+4(1)=16 g
0.462 L(0.462 dm^3) at STP of CH4
=(16 g×0.462 dm^3)/22.4 dm^3
=0.33 g
