How many oxygen atoms are in 15.0 grams of Magnesium phosphate?

8 atoms of oxygen.

Explanation:

Given parameter:

Mass of magnesium phosphate  = 15g

Unknown:

Number of oxygen atoms  = ?

Solution:

The formula of the compound is;

        Mg₃(PO₄)₂;

 Number of atoms oxygen  = 2(4) = 8 atoms of oxygen.

there are two significant figures.

answer; the numbers of valence electrons in the acetic acid molecule (ch3co2h) is 24;