Question

Identify the valency of element X in the following compounds.
a) $X{H}_3$ b) $XC{l}_5$
c) $X_2{O}_3$ d) $X{O}_2$

Answer 1

(a) If $X{H}_3$ is a hydride, then valency of $X$ is $+3$ or else it is $-3$.

(b) In $XC{l}_5$, $5C{l}^{-}$ are there. Therefore valency of $X$ is $+5$.

(c) In $X_2{O}_3$, three $O^{2-}$ are present. Let $y$ be valency of $X$. Then $2y=3\times 2\Rightarrow y=+3$

Valency of $X$ is $+3$

(d) In $X{O}_2$, if it is an oxide, valency of $X$ is $+4$. If it is a peroxide, valency of $X$ is $+2$. If it is a superoxide, valency of $X$ will be $+1$.