Question:
Which of the following represents a correct chemical formula? Name it.
(a) $\mathrm{CaCl}$
(b) $\mathrm{BiPO}_{4}$
(c) $\mathrm{NaSO}_{4}$
(d) NaS.
Solution:
(b). Both Bi and $\mathrm{PO}_{4}$ are trivalent ion $\left(\mathrm{Bi}^{3+}\right.$ and $\left.\mathrm{PO}_{4}{ }^{3-}\right)$.
It is known as bismuth phosphate.