Question

Select the compound in which chlorine shows oxidation state of $+3$ ?

• A. $Cl{O}_4^{-}$
• B. $Cl{O}_3^{-}$
• C. $Cl{O}_2^{-}$
• D. $Cl{O}^{-}$

Answer 1

Answer: (C)

Let the oxidation number of $Cl=x$.
(i) $Cl{O}_4^{-}:x+(-2\times 4)=-1$
$x-8=-1,x=+7$
(ii) $Cl{O}_3^{-}:x+(-2\times 3)=-1$
$x-6=-1,x=+5$
(iii) $Cl{O}_2^{-}:x+(-2\times 2)=-1$
$x-4=-1,x=+3\text{. }$
(iv) $Cl{O}^{-}:x+(-2)=-1$
$x-2=-1,x=+1$
Thus, $Cl{O}_2^{-}$shows oxidation state of $+3$.