Question

Which one of the following is a compound?

• A. Carbon dioxide
• B. Iron
• C. Oxygen
• D. Nitrogen

Answer 1

The correct option is A

Carbon dioxide

An explanation for the correct option

(A) Carbon dioxide

Compound

• A compound is a substance made up of two or more elements that have been chemically mixed in a certain proportion.
• Examples of compounds are Baking soda $\left({\mathrm{NaHCO}}_3\right)$, Ammonia $\left({\mathrm{NH}}_3\right)$.
• 4. It cannot be separated into its constituents by simple physical means.
• 
  Carbon dioxide
• The elements carbon and oxygen from Carbon dioxide $\left({\mathrm{CO}}_2\right)$.
• Hence, it is a compound.

An explanation for incorrect options

(B) Iron

• Iron $\left(\mathrm{Fe}\right)$ is a pure element.

(C) Oxygen

• Oxygen $\left({\mathrm{O}}_2\right)$ gas is a molecule.
• It is made up of only one element, oxygen.

(D) Nitrogen

• Nitrogen $\left({\mathrm{N}}_2\right)$ gas is a molecule.
• It is made up of only one element, nitrogen.

Therefore, the correct option is (A) Carbon dioxide.