Final answer:
Calcium hydride (CaH₂) acts as a reducing agent in its reaction with water, providing electrons and thereby getting oxidized to calcium hydroxide (Ca(OH)₂) while releasing hydrogen gas (H₂) (d).
Step-by-step explanation:
In the reaction where calcium hydride (CaH₂) is involved, particularly the reaction of CaH₂ with water, CaH₂ acts as a reducing agent.
Reducing agents are substances that donate electrons to another substance in a redox (reduction-oxidation) reaction, thereby getting oxidized themselves. In the reaction CaH₂ (s) + 2H₂O(l) → Ca(OH)₂ (aq) + 2H₂(g), CaH₂ provides electrons for the reduction process to occur. This means that hydrogen atoms from CaH₂ gain electrons to form hydrogen gas (H₂), and in doing so, calcium hydride itself is oxidized from CaH₂ to Ca(OH)₂.
In the given reaction, CaH₂ acts as a reducing agent. A reducing agent is a substance that donates electrons and causes another substance to be reduced. In this reaction, CaH₂ donates hydrogen atoms (H⁻) to the reactants, causing them to be reduced. Therefore, the correct answer is d. It is a reducing agent.