Concept:Some amphoteric metals react with hot concentrated alkaline solutions to liberate hydrogen gas.
Explanation:Tin (
Sn) is the metal among the options that displaces hydrogen from a hot alkaline solution.
Iron, copper, and calcium do not show this typical reaction with hot alkali.
Tin dissolves in hot concentrated alkali to produce a trioxostannate(IV) salt and hydrogen gas (
H2).
This happens because tin is amphoteric, so it reacts with both acids and strong bases.
The reaction only occurs with hot alkaline solutions, not with cold dilute alkalis.
Therefore, tin is the metal that displaces hydrogen under these conditions.
Answer:D. Sn