Question

In $KH$ , the oxidation number of hydrogen is:
A. +2
B. +1
C. 0
D. -1
E. -2

Answer 1

Oxidation number is a number assigned to an element in chemical combination which represents the number of electrons lost if the number is positive or gained, if the number is negative, by an atom of that element in the compound.

Complete step by step solution:
First of all we should know the definition of oxidation number.
Oxidation number is the number which represents the number of electrons lost or gained by an atom of that element in the compound.
So according to this definition the oxidation number of $K$ in $KH$ is +1 as $K$ is having 1 valence electron so it will lose 1 electron and hydrogen $H$ will gain 1 electron. So the oxidation number of hydrogen is -1.

So the correct option is D.

Additional Information:
The oxidation number of $H$ is +1, but it is -1 when combined with less electronegative elements.

Note:
It is to be noted that the oxidation number of a free element is always zero. And also the same element can have more than one oxidation number depending upon the compound or the types of elements with which it is combined.