Question

If the molecular formula of aluminium sulphate is $A{l}_2(S{O}_4{)}_3$, then the valencies of aluminium and the sulphate radical are:

• A. 2, 2
• B. 2, 3
• C. 3, 3
• D. 3, 2

Answer 1

The correct option is D 3, 2

Aluminium sulphate: $A{l}_2(S{O}_4{)}_3$
The ions present here are $A{l}^{3+}and(S{O}_4{)}^{2-}$
$A{l}^{3+}$ is a monoatomic ion whose valency is 3.
$(S{O}_4{)}^{2-}$ is a polyatomic ion whose valency is 2.