Question

Oxidation number of $S$ in $S{O}_4^{2-}:$

• A. 6
• B. 3
• C. 2
• D. -2

Answer 1

Answer: (A)

The sum of oxidation states of all elements in an ion is equal to charge on it. Let the oxidation state of $S$ in $S{O}_4^{2-}=x$
$\therefore x+(-2\times 4)=-2$
or $x=+6$