Question

$1lte$ of mole of oxygen in one litre of air containing $21$% oxygen by volume, under standard conditions, is:

• A. $0.0093mole$
• B. $0.235mole$
• C. $0.456mole$
• D. none of these

Answer 1

Answer: (A)

$0.0093mole$

Volume of $O_2$ in $1L$ air $=1000$ $c{m}^3\times 0.21=210$ $c{m}^3$

At, STP $1$ $mole$ $O_2$ occupies $22400$ $c{m}^3$ volume.

$\therefore x$ $mole$ $O_2$ occupies $210$ $c{m}^3$ volume

$x=\frac{210}{22400}=9.375\times {10}^{-3}=0.00937$ $mole$