Question

When $C{l}^{-}$ ions are converted to $C{l}_2$ , the oxidation number of chlorine changes from:

• A. $-1$ to $0$
• B. $-1$ to $+1$
• C. $-1$ to $+2$
• D. $-2$ to $0$

Answer 1

Answer: (A)

$-1$ to $0$

In $C{l}^{-}$, oxidation number of $Cl$ is $-1$.
In $C{l}_2$, oxidation state is zero.
Hence, the oxidation state changes from $-1$ to $0$.