Question

which of the following is an element? cu(so₄)₃, mgbr, o₂, hcl

Explanation:

Step1: Recall element definition

An element is a pure substance made of only one type of atom. Compounds have two or more different atoms.

Step2: Analyze each option

• \( \text{Cu(SO}_4\text{)}_3 \): Contains Cu, S, O – compound.
• \( \text{MgBr} \): Contains Mg and Br – compound.
• \( \text{O}_2 \): Made of only O atoms – element.
• \( \text{HCl} \): Contains H and Cl – compound.

Answer:

\( \text{O}_2 \) (the option with \( \text{O}_2 \))