Question

the chemical formulas for several different substances are shown. select all pove that are pure elements. selected answers appear shaded. o₂ fe h₂o nh₃ co₂ n₂ al nacl c

Explanation:

Step1: Recall definition of elements

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

Step2: Analyze each chemical formula

• $O_2$: Composed of only oxygen atoms, it is an element.
• $Fe$: Composed of only iron atoms, it is an element.
• $H_2O$: Composed of hydrogen and oxygen atoms, it is a compound.
• $NH_3$: Composed of nitrogen and hydrogen atoms, it is a compound.
• $CO_2$: Composed of carbon and oxygen atoms, it is a compound.
• $N_2$: Composed of only nitrogen atoms, it is an element.
• $Al$: Composed of only aluminum atoms, it is an element.
• $NaCl$: Composed of sodium and chlorine atoms, it is a compound.
• $C$: Composed of only carbon atoms, it is an element.

Answer:

$O_2$, $Fe$, $N_2$, $Al$, $C$