Question

Which of the following is not a compound?

• A. Ozone
• B. Sugar
• C. Water
• D. Salt

Answer 1

The correct option is A

Ozone

Explanation for correct option:

A. Ozone

Compounds:

• “A compound is a substance composed of two or more elements, chemically combined with one another in a fixed proportion.”
• The composition of each formed substance is always fixed.
• Examples of Compounds are Sodium chloride$\left(\mathrm{NaCl}\right)$ as well as Water $\left({\mathrm{H}}_2\mathrm{O}\right)$.

Thus, Ozone$\left({\mathrm{O}}_3\right)$ is not a compound as it has three identical oxygen atoms.

Explanation for incorrect options:

Water, Salt, and Sugar are examples of compounds as they are composed of more than two different atoms. Thus, Options B, C, and D are incorrect.

Hence, the correct option is A i.e. Ozone is not a compound.