Question

What will be the oxidation number of underlined element : $KAl(\underset{–}{S}{O}_4{)}_2.12H_{2}O$

• A. $+2$
• B. $+6$
• C. $-2$
• D. $+3$

Answer 1

The correct option is B $+6$

For $KAl(\underset{–}{S}{O}_4{)}_2.12H_{2}O$
Let, the oxidation state of $S$ be $x$ in $KAl(\underset{–}{S}{O}_4{)}_2.12H_{2}O$
Oxidation number of $K=+1$
Oxidation number of $Al=+3$
Oxidation number of $O=-2$
Oxidation number of $H=+1$
$+1+3+2x+3(-2)+12(2\times 1-2)=0$
$x=+6$