COMEDK · Chemistry · 3. Classification of Elements and Periodicity in Properties

Which of the following is an INCORRECT match?

A Electron Gain enthalpy - \(F < Cl > Br > I\)
B Metallic character - \(Al > Mg > B > K\)
C First Ionization Enthalpies - \(Na < Mg > Al < Si\)
D Ionic size - \(\text{Na}^+ > \text{Mg}^{+2} > \text{Al}^{+3} > \text{Si}^{+4}\)

Verified Solution

Answer & Solution

Correct Answer

(B) Metallic character - \(Al > Mg > B > K\)

Step-by-step Solution

Detailed explanation

Metallic character increases down a group and decreases from left to right across a period. Potassium (\(K\)) is an alkali metal in group 1 and period 4, making it the most metallic among the given elements. Boron (\(B\)) is a metalloid in group 13 and period 2, making it the…

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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