Question

Which one of the following metals does not react with cold as well as hot water?

• A. $\mathrm{Na}$
• B. $\mathrm{Ca}$
• C. $\mathrm{Mg}$
• D. $\mathrm{Fe}$

Answer 1

The correct option is D

$\mathrm{Fe}$

Explanation for correct option

(D) $\mathbf{Fe}$

Reactivity of metal with water

• Metal hydroxide and hydrogen gas are produced when some metals react with water.
• Metals with lower activity react with boiling water.

Iron reactivity with cold and hot water

• When exposed to both hot and cold water, the less reactive metal Iron $\left(\mathrm{Fe}\right)$ does not react.
• But when the iron is combined with steam causes the formation of metal oxides and hydrogen gas.
• The reaction is as follows:

$3\mathrm{Fe}\left(\mathrm{s}\right)+4{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)\to {\mathrm{Fe}}_3{\mathrm{O}}_4\left(\mathrm{s}\right)+4{\mathrm{H}}_2\left(\mathrm{g}\right)$

Explanation for incorrect options

• Reactive metals such as Sodium $\left(\mathrm{Na}\right)$, Calcium $\left(\mathrm{Ca}\right)$, etc., react with cold or hot water.
• Metals like Magnesium $\left(\mathrm{Mg}\right)$ that are moderately reactive react with boiling water.
• Hence, all other options (A), (B), and (C) are incorrect.

Therefore, the correct option is (D) $\mathbf{Fe}$.