Answer : 9.89 L
Explanation;
The balanced reaction equation is
2Ca(s) + O₂(g)→ 2CaO(s)
Moles (mol) = Mass (g) /Molar mass (g/mol)
Mass of Ca = 35.4 g
Molar mass of Ca = 40.08 g/mol
Hence, moles of Ca = 35.4 g /40.08 g/mol
= 0.883 mol
The stoichiometric ratio between Ca and O₂ is 2 : 1.
Hence,
reacted moles of O₂ = moles of Ca / 2
= 0.883 mol / 2
= 0.4415 mol
Let's assume that O₂ is an ideal gas.
1 mole of ideal gas has the volume as 22.4 L at STP (273 K , 1 atm)
Hence,
volume of 0.4415 mol of O₂ = 22.4 L mol⁻¹ x 0.4415 mol
= 9.8896 L
= 9.89 L