# Question #eaed5

Feb 28, 2016

trying to clear

#### Explanation:

${H}_{3} P {O}_{4}$ is a tri-basic acid i.e. it has got 3 replaceable H atoms in its molecule as is evident from its structural formula below

In our equation one atom of the acid molecule has been replaced i.e.${H}_{2} P {O}_{4}^{-} 1$is contributed by the acid. So 2 of this ion will combine with one$C {a}^{+ +}$ forming $C a {\left(H P {O}_{4}\right)}_{2}$

When two atoms are replaced then$H P {O}_{4}^{-} 2$ ion is formed and one of this divalent ion combine with one $C {a}^{+ +}$ ion forming $C a H P {O}_{4}$

Finally when 3 H atoms are replaced then $P {O}_{4}^{-} 3$ ion is formed and two of this ion combine with 3 $C {a}^{+ +}$ ions forming $C {a}_{3} {\left(P {O}_{4}\right)}_{2}$

Brackets are used to separate the positive and negative groups / ions not equal in numbers

pls, inform if cleared