Stoichiometry uses the balanced chemical equation to relate moles of reactants and products. The balanced equation shows that 1 mol of propane requires 5 mol of oxygen. First, find the moles of propane: (n_{\text{C}_3\text{H}_8} = 2.2/44 = 0.05) mol. From the mole ratio, moles of (\text{O}_2) required (= 0.05 \times 5 = 0.25) mol. Option 0.05 mol is the number of moles of propane itself, not oxygen — the mole ratio has not been applied. Option 0.50 mol is double the correct value and would correspond to 10 mol of (\text{O}_2) per mol of propane, not 5. Option 1.00 mol is 4 times the correct answer and arises from an incorrect mole ratio of 20:1 instead of 5:1. This is a direct NCERT stoichiometry calculation requiring mole ratio from a balanced equation. Plausibility check: 0.25 mol of (\text{O}_2) has mass (0.25 \times 32 = 8) g, which is reasonable for burning a small amount of propane.