Question

Give one word for the following -
the gas which makes up about one-fifth of air

Answer 1

• Air is a mixture of gases like nitrogen, oxygen, carbon dioxide, and some other gases.
• By volume, air contains $78\%$ nitrogen $\left({\mathrm{N}}_2\right)$, $21\%$ oxygen $\left({\mathrm{O}}_2\right)$, $0.93\%$ argon $\left(\mathrm{Ar}\right)$,$0.03\%$ carbon dioxide$\left({\mathrm{CO}}_2\right)$, and trace amounts of other gases.
• Hence, the gas which makes up about one-fifth of air is oxygen.
• Oxygen ,making $21\%$ is one-fifth of $100\%$. i.e., $\frac{100\%}{5}$ which is approximately equal to $21\%$.

So, the gas which makes up about one-fifth of air is oxygen.