Question

The number of moles of oxygen in one litre of air containing 21% oxygen by volume, under standard conditions is __________.

• A. 0.0093 moles
• B. 2.10 moles
• C. 0.18 moles
• D. 0.21 moles

Answer 1

The correct option is A 0.0093 moles

Volume of $O_2=\frac{21}{100}\times 1000=210\text{mL}$

Moles of $O_2$ at STP$=\frac{210}{22400}=0.0093\text{mole}$