Question

Match the chemical formula and chemical name for the following compounds

• A. (i) $Al(OH{)}_3$
• B. (ii) $KN{O}_3$
• C. (iii) $CaC{O}_3$

Answer 1

Valency of Al is 3 and hydroxide ion has charge -1.
So, by criss cross method, $Al(OH{)}_3$ is the chemical formula of aluminium hydroxide
Valency of Ca is 2, carbonate ion i.e, $(C{O}_3{)}^{–2}$ has charge 2
By criss cross method , the formula is $CaC{O}_3$. It won't be $C{a}_2(C{O}_3{)}_2$ since it has same number on both the ions so, it can be written as $CaC{O}_3$
Valency of K is 1, nitrate has charge -1.
So by criss cross method, the formula of potassium nitrate is $KN{O}_3$.