2 Caz (PO4)2
How many phosphorus atoms are there in the
picture?

4 phosphorus

Explanation:

The given compound is:

             2Ca₃(PO₄)₂

We have been given 2 moles of Ca₃(PO₄)₂ . The number of atoms is the same as the number of elements present within the compound. Since this is 2 moles, we multiply every number of atoms by 2;

      2Ca₃(PO₄)₂

Ca :  2 x 3  = 6 atoms

P :  2 x 2  = 4 atoms

O:  2 x (2 x 4) = 16 atoms

So we have 4 phosphorus atoms