-<u><em>Oxygen</em></u>
According to Google these are the percentages of the <em>Earths Atmosphere</em>
<em>1</em> 78% - Nitrogen
<u>2</u> 21% - Oxygen
<em>3</em> 0.9% - Argon
<em>4 </em>0.3 - Carbon Dioxide with very small percentage of other elements.
I believe the answer is B. PO4-3
Explanation:
Here I send you all the 3 elements that you are asking for.
Notice that first on the left you will find lewis structure, then condensed and finally chemical formula of each of the compound you enlisted.
1.12 miles of MgCl2 will be produced from the 32.0 of Mg(OH)2