AIIMS2017Chemistry-Periodic Table

AIIMS 2017 Chemistry Alkali Metals Assertion Reason Question

Type: Assertion Reason-conceptual-Medium-Class 11

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct answer out of the following choice.

Assertion (A) Generally alkali and alkaline earth metals form superoxides.

Reason (R) There is a single bond between O and 0 in superoxides.

A

Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.

B

Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.

C

Assertion is correct but Reason is incorrect.

D

Both Assertion and Reason are incorrect.

Correct Answer

Option A

Detailed Explanation

Option A is correct because both the assertion and reason are true: alkali metals such as potassium (K), rubidium (Rb), and cesium (Cs) do indeed form superoxides (e.g., KO₂), and superoxides contain the O₂²⁻ ion, which features a bond between two oxygen atoms, but it is not a double bond; rather, it has a unique bonding structure involving a superoxide ion. Other options are incorrect because option B suggests the reason is not a correct explanation, which is misleading as the bonding nature in superoxides is relevant to the assertion; option C incorrectly states that the assertion is true while the reason is false; and option D incorrectly claims both statements are false. Understanding the structure of superoxides is essential for grasping the unique chemistry of alkali metal oxides.

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