Question

Choose the given reaction(s) in which water act as an oxidising agent.

• A. $Mg+2H_{2}O\to Mg(OH{)}_2+H_2$
• B. $Ca{H}_2+2H_{2}O\to Ca(OH{)}_2+2H_2$
• C. $2F_2+2H_{2}O\to 4HF+O_2$
• D. $2Na+2H_{2}O\to 2NaOH+H_2$

Answer 1

Answer: (A), (B), (D)

$2Na+2H_{2}O\to 2NaOH+H_2$

The $H^{+}$ ion in water get reduced from +1 to 0 oxidation state and liberate as $H_2$ gas.
Hence in option (a), (b) and (d) $H_2$ is produced hence it shows that $H^{+}$ is reduced. Thus water is a oxidising agent.
In option (c), the $O{H}^{-}$ ion of water get oxidise from -2 to 0 oxidation and liberate as $O_2$ gas. Hence in option(c) water is acts as a reducing agent, it reduced $F_2$ to $F^{-}$.
Hence option (a), (b) and (d) are correct.