Question

2.. Air contains 21% of oxygen by volume. How many number of moles of O2 are present in 5 litres
of air at STP?​

Answer 1

$\huge\fbox\red{A}\fbox\pink{N}\fbox\green{S}\fbox\blue{W}\fbox\purple{E}\fbox\orange{R}$

Let the volume of solute be V litre and the volume of the solution (which is the volume of air) is given to be 1 L. So, we can now say the number of moles of oxygen in 1 L of air containing 21% oxygen by volume, in standard conditions, is 0.0093 mol.

Answer 2

$\huge\sf\color{red}{คภ}\color{yellow}{នฬ}\color{lime}{єг}\color{blue}{:}$

Let the volume of solute be V litre and the volume of the solution (which is

the volume of air) is given to be 1 L. So, we can now say the number of moles of oxygen in 1 L of air containing 21% oxygen by volume, in standard conditions, is 0.0093 mol.