State the number of atoms present in each of the following chemical species:
$(a)$ $CO_{3}^{2-}$
$(b)$ $PO_{4}^{3-}$
$(c)$ $P_{2}O_{5}$
$(d)$ $CO$

(A) $CO_{3}^{2-}$ consists of $1$ carbon atom and $3$ oxygen atoms,totaling $1 + 3 = 4$ atoms.
$(b)$ $PO_{4}^{3-}$ consists of $1$ phosphorus atom and $4$ oxygen atoms,totaling $1 + 4 = 5$ atoms.
$(c)$ $P_{2}O_{5}$ consists of $2$ phosphorus atoms and $5$ oxygen atoms,totaling $2 + 5 = 7$ atoms.
$(d)$ $CO$ consists of $1$ carbon atom and $1$ oxygen atom,totaling $1 + 1 = 2$ atoms.