Question

Which among the following are elements?

• A. Chlorine
• B. Water
• C. Nitrogen
• D. Carbon dioxide

Answer 1

Answer: (A), (C)

Nitrogen

Elements are made of up only one kind of atoms. Among the given options, chlorine $\left({\text{Cl}}_2\right)$ and nitrogen $\left({\text{N}}_2\right)$, are made of only one kind of atoms i.e. chlorine and nitrogen respectively. So, they are elements.

Compounds are made up of two or more kinds of atoms, chemically combined, in a definite ratio. Water $\left({\text{H}}_2\text{O}\right)$ is made of hydrogen and oxygen in a ratio of 2:1 and carbon dioxide $\left({\text{CO}}_2\right)$ is made of carbon and oxygen in a ratio of 1:2. Hence, they are compounds.