Question

An element "Z" of valency 2 forms its sulphate with chemical formula ${ZSO}_4$. Find:
(i) the ions present in the compound.
(ii) the chemical formula of its nitride.
(iii) the chemical formula of its hydroxide.
[5 Marks]

Answer 1

(i) Given that the chemical formula of the sulphate containing element "Z" is ${ZSO}_4$ and the valency of Z is 2.
Thus, the ions present in the compound are: $Z^{2+}$ and ${SO}_4^{2-}$

[1 Mark]

(ii) Valency of $Z^{2+}$ = 2
Valency of nitride ion ($N^{3-}$) = 3

Symbol	Z	N
Valency	2	3

Upon criss-crossing the valencies, we get $Z_3{N}_2$ as the chemical formula of the nitride of $Z$.
[2 Marks]

(iii) Valency of $Z^{2+}$ = 2
Valency of hydroxide ion (${OH}^{-}$) = 1

Symbol	Z	OH
Valency	2	1

Upon criss-crossing the valencies, we get ${Z\left(OH\right)}_2$ as the chemical formula of the hydroxide of $Z$.
[2 Marks]