Chemistry 2003 JAMB Past Questions - Question 33: Hydrogen can be displaced from a hot alkaline solution by

Correct Answer

A

Explanation

Hydrogen can be displaced from a hot alkaline solution by zinc (Zn) rather than the options you've listed. When zinc is added to a hot alkaline solution, it can displace hydrogen gas, resulting in the formation of zinc hydroxide and the release of hydrogen gas.

Hydrogen gas can be displaced from a hot alkaline solution by certain metals that are more reactive than hydrogen. The reactivity series of metals helps determine which metals can displace hydrogen from a solution of its salts. The reactivity series generally follows the order:

\[ \text{K} \,>\, \text{Na} \,>\, \text{Ca} \,>\, \text{Mg} \,>\, \text{Al} \,>\, \text{Zn} \,>\, \text{Fe} \,>\, \text{Ni} \,>\, \text{Sn} \,>\, \text{Pb} \,>\, \text{H} \]

Here, \( \text{Fe} \) (iron) is higher in the reactivity series than \( \text{H} \) (hydrogen). Therefore, in a hot alkaline solution, iron (\( \text{Fe} \)) can displace hydrogen and release hydrogen gas.

However, copper (\( \text{Cu} \)), calcium (\( \text{Ca} \)), and tin (\( \text{Sn} \)) are not reactive enough to displace hydrogen from a hot alkaline solution. These metals are lower in the reactivity series than hydrogen, so they cannot displace hydrogen under normal conditions.

It's important to note that the specific conditions (such as concentration, temperature, and the nature of the solution) can influence the reactivity of metals, so reactions may vary under different circumstances.