AP EAMCET · Chemistry · s Block Elements

Assertion (A): $K, Rb$ and $Cs$ form superoxides
Reason (R): The stability of superoxides increases form $K$ to $Cs$ due to decrease in lattice energy.

A Both $A$ and $R$ are true and $R$ is a correct explanation for $A$
B Both $A$ and $R$ are true but $R$ is not a correct explanation for $A$
C $A$ is true, $R$ is false
D $A$ is false, $R$ is true

Verified Solution

Answer & Solution

Correct Answer

(C) $A$ is true, $R$ is false

Step-by-step Solution

Detailed explanation

K, Rb, Cs form superoxides when they are burnt in the air. As we down the group then the size of atom from K to Cs increases so that the lattice energy decreases hence the stability of superoxide also decreases.

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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Assertion (A): K, Rb and Cs form superoxidesReason (R): The stability of superoxides increases form K to Cs due to decrease in lattice energy.

Step-by-step Solution

Assertion (A): $K, Rb$ and $Cs$ form superoxides
Reason (R): The stability of superoxides increases form $K$ to $Cs$ due to decrease in lattice energy.