Question

Assertion: Oxidation state of hydrogen is +1 in $H_{2}O$ while -1 in $Ca{H}_2$.
Reason: $Ca{H}_2$ is a metal hydride and for hydrides, hydrogen is assigned the oxidation number of -1.

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Answer 1

Oxidation number of elements in their compounds or ions is obtained using some rules.
E.g., Hydrogen is assigned oxidation number of +1 in general and -1 for metal hydrides.
Hence, both Assertion and Reason are true and Reason is the correct explanation for Assertion.