Question

The total number of atoms represented by the formula Fe3(PO4)2 is
A. 11
B. 12
C. 13
D. 15

Answer 1

C is the answer 3 + 2 +8 = 13

Answer 2

Answer:

C.

Explanation:

We have to keep in mind for this question that we have to take into account the subscripts.

$Fe_3(PO_4)_2$

The subscript will affect only the number in the left, so the first part would be:

$Fe_3$

In this part we will have 3 iron atoms. Then we will have:

$(PO_4)_2$

In the $PO_4$ we will have 1 atom of P and 4 atoms of O. (When we dont have any number as subscript we have to assume that we have a "1")

Then we have a "2" out side the the parenthesis $(PO_4)_2$, so we have to multiply by "2" all the atoms inside the parenthesis, so:

1 atom of P x 2 = 2

4 atoms of O x 2 = 8

So, in total we will have:

3 atoms of Fe + 8 atoms of O + 2 atoms of P = 13 atoms