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Which of the following facts provide evidence for the ionic nature of lithium hydride (LiH)?

1. Molten LiH (m.p. 691 deg C) conducts electricity
2. H2 is liberated at the anode on electrolysis of molten LiH
3. When LiH reacts with water it liberates H2
4. Li gets deposited at the cathode on electrolysis of molten LiH

Correct answer: Molten LiH (m.p. 691 deg C) conducts electricity

Solution

Molten LiH conducts electricity because it contains Li+ and H- ions that are free to move; this is direct evidence of ionic character. Options B and D also support ionicity (H- oxidised at anode, Li+ reduced at cathode) but are consequences rather than primary evidence. The most direct single answer is option A (conduction in molten state).

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