Question

Which of the following is an example of a molecule of an element?

• A. ${\text{H}}_{2}O$
• B. ${\text{NH}}_3$
• C. ${\text{CO}}_2$
• D. ${\text{O}}_2$

Answer 1

The correct option is D ${\text{O}}_2$

${\text{O}}_2$ is a molecule made up of 2 oxygen atoms. Therefore, it is an example of a molecule of an element.

However, ${\text{NH}}_3$ contains 1 N and 3 H atoms, ${\text{H}}_{2}O$ contains 2 H and 1 O atom and ${\text{CO}}_2$ contains 1 C and 2 O atoms. Therefore, they are considered as molecules of compounds.