Question

Oxidation state of $H$ in $LiH$is

• A. 1
• B. -1
• C. 2
• D. -2

Answer 1

The correct option is B -1

The oxidation number of hydrogen is + 1 when it is combined with non-metals and it is -1 when it is combined with active metals called metal hydrides such as $LiH,KH,Mg{H}_2,Ca{H}_2$ etc.
We can also verify this by calculating the oxidation number of $H$ in $LiH$
Let the oxidation number of H be $x$

In the compound given to us the oxidation number of Li is+1 as it is a metal. So, we can obtain the equation for the sum of oxidation numbers of elements in the compounds as

$LiH\Rightarrow 1+x=0$

$x=-1$
Hence, the oxidation number of H is -1