Question

In which of the following reactions, hydrogen is acting as an oxidising agent?

• A. With iodine to give hydrogen iodide
• B. With lithium to give lithium hydride
• C. With nitrogen to give ammonia
• D. With sulphur to give hydrogen sulphide

Answer 1

The correct option is B With lithium to give lithium hydride

An oxidising agent itself undergoes reduction. Its oxidation number decreases. When $H_2$ is converted to hydride ion $H^{-}$, it itself is reduced and acts as oxidisng agent.

In the following reactions, hydrogen is acting as an oxidising agent.

With lithium to give lithium hydride

$H_2+2Li\to 2LiH$

In the following reactions, hydrogen is acting as a reducing agent.

With iodine to give hydrogen iodine

$H_2+I_2\to 2HI$

With nitrogen to give ammonia

$3H_2+N_2\to 2N{H}_3$

With sulphur to give hydrogen sulphide

$H_2+S\to H_{2}S$