Question

The oxidation state of the $C$ atom in $HCN$ molecule is

• A. +1
• B. +2
• C. -2
• D. -1

Answer 1

The correct option is B

+2

In compounds formed by the union of different elements, the more electronegative atom will have negative oxidation number whereas the less electronegative atom will have positive oxidation number.

Here N is more electronegative than C.

Further, the oxidation number of hydrogen is + 1 when combined with non-metals and is -1 when combined with active metals called metal hydrides such as $LiH,KH,Mg{H}_2,Ca{H}_2$ etc.

Therefore, the O. N. (N) = -3

O. N. (H) = +1

HCN $⟹$ +1+n-3 = 0

$⟹$ C = 2