Question

1. choose the best answer. how many oxygen atoms are in h₂o (water)? 2 3 4 1 7) choose the best answer. which molecule has sodium and hydrogen molecules? ch₃cooh naoh hno₃ na₃po₄

Explanation:

Step1: Analyze water formula

The chemical formula of water is $H_2O$. The sub - script after the element symbol indicates the number of atoms of that element in the molecule. For oxygen in $H_2O$, the sub - script is 1, so there is 1 oxygen atom.

Step2: Analyze molecule components

For the second question, we look at the chemical formulas of the given substances.

• $CH_3COOH$ contains carbon, hydrogen and oxygen.
• $NaOH$ contains sodium ($Na$), oxygen and hydrogen.
• $HNO_3$ contains hydrogen, nitrogen and oxygen.
• $Na_3PO_4$ contains sodium, phosphorus and oxygen. So the molecule with sodium and hydrogen is $NaOH$.

Answer:

1. D. 1
2. B. $NaOH$