Question

The sum of oxidation number of all atoms in $\mathrm{S_2O_3^{2-}}$ ion is

• A. $+2$
• B. $+5$
• C. $-2$
• D. $+7$

Hint:

For any ion, the sum of oxidation numbers always equals the ionic charge.

Answer 1

The Correct Option is C

Step 1: Rule for oxidation numbers.
The algebraic sum of oxidation numbers of all atoms in a polyatomic ion is equal to the net charge on the ion.

Step 2: Charge on thiosulphate ion.
The charge on $\mathrm{S_2O_3^{2-}}$ ion is $-2$.

Step 3: Conclusion.
Hence, the sum of oxidation numbers of all atoms present in $\mathrm{S_2O_3^{2-}}$ is $-2$.