Question

If $M^{+3}$ ion gains $2e^{-}$. Its oxidation number will be

• A. 2
• B. 1
• C. -1
• D. -2

Answer 1

The correct option is B 1

Oxidation number is the total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom.
Looking at the ion $M^{3+}$ clearly, the oxidation number is +3.

Further ,$M^{3+}$ gains 2 electrons to become $M^{1+}$.

Hence, the new oxidation number is +1.