Question

elementcompound1. select all the element(s) from the following substances. o₂ p₄ he c₂h₄o₂ fe₂o₃

Explanation:

Step1: Recall element definition

An element is a pure - substance made of only one type of atom.

Step2: Analyze $\text{O}_2$

$\text{O}_2$ is oxygen gas, made of only oxygen atoms.

Step3: Analyze $\text{P}_4$

$\text{P}_4$ is white - phosphorus, made of only phosphorus atoms.

Step4: Analyze $\text{He}$

$\text{He}$ is helium, a noble gas made of only helium atoms.

Step5: Analyze $\text{C}_2\text{H}_4\text{O}_2$

$\text{C}_2\text{H}_4\text{O}_2$ (e.g., acetic acid) is made of carbon, hydrogen, and oxygen atoms, so it is a compound.

Step6: Analyze $\text{Fe}_2\text{O}_3$

$\text{Fe}_2\text{O}_3$ (iron(III) oxide) is made of iron and oxygen atoms, so it is a compound.

Answer:

1. $\text{O}_2$, $\text{P}_4$, $\text{He}$