Answer: Oxygen
Explanation:
[tex]2H_2+O_2\rightarrow 2H_2O[/tex]
As seen from the balanced equation:
2 moles of hydrogen combine with 1 mole of oxygen or 1 mole of hydrogen combine with 1/2 mole of oxygen.
According to Avogadro's law, equal volumes of gases contain equal number of molecules and hence equal number of moles.
Thus if x moles of both gases are present, x moles of hydrogen will combine with [tex]\frac{x}{2}[/tex] moles of oxygen and [tex]x-\frac{x}{2}=\frac{x}{2}[/tex] moles of oxygen will be left used and will be in excess.
