Question

which of the following correctly counts the atoms in ca₃(po₄)₂?
3 ca, 2 p, 8 o
1 ca, 2 p, 4 o
3 ca, 2 p, 4 o
3 ca, 4 p, 6 o

Explanation:

Step1: Count Ca atoms

The subscript of Ca is 3, so there are 3 Ca atoms.

Step2: Count P atoms

The subscript of P in \(PO_4\) is 1, and there are 2 \(PO_4\) groups (due to the outer subscript 2). So the number of P atoms is \(1\times2 = 2\).

Step3: Count O atoms

The subscript of O in \(PO_4\) is 4, and there are 2 \(PO_4\) groups. So the number of O atoms is \(4\times2=8\).

Answer:

3 Ca, 2 P, 8 O