As we know that 1 mole of any gas when acting perfectly / ideally occupies 22.4 L of volume.
It means that in order to calculate volume occupied both by CH₄ and He, we must calculate their moles.
Hence,
Moles are given as,
Moles = Mass / Mass
Moles of CH₄;
Mole-CH₄ = 4 g / 16 g.mol⁻¹
Mole-CH₄ = 0.25 mol
Moles of He;
Mole-He = 2 g / 4 g.mol⁻¹
Mole-He = 0.5 mol
Now adding moles of both gases,
= 0.25 + 0.5
= 0.75 mol
Therefore, when,
1 mole of gas occupy = 22.4 L of Volume
Then,
0.75 mol will occupy = X L of Volume
Solving for X,
X = (0.75 mol × 22.4 L) ÷ 1 mole
X = 16.8 L
