Question

If 1 in every 5 parts of air is oxygen, then the percentage of oxygen in air is

• A. 1.5%
• B. 5%
• C. 25%
• D. 20%

Answer 1

The correct option is D 20%

Total parts of air = 5
Parts of oxygen = 1
Fraction of oxygen in air = $\frac{1}{5}$

Percentage is a fraction with its denominator as 100.

Converting $\frac{1}{5}$ into a fraction with denominator 100, you get:

$\frac{1}{5}=\frac{1\times 20}{5\times 20}=\frac{20}{100}$

So, the percentage form of $\frac{1}{5}$ is $20\%$.

∴ The percentage of oxygen in air is $20\%$.