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.

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> AIIMS 2018

• A. Both Assertion and Reason are false.
• B. Both Assertion and Reason are true and Reason is the correct explanation for Assertion.
• C. Both Assertion and Reason are true but Reason is not the correct explanation for Assertion.
• D. Assertion is true but Reason is false.

Answer 1

The correct option is B Both Assertion and Reason are true and Reason is the correct explanation for Assertion.

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.