Question

Which of the following order is wrong?

• A. NH₃
• B. Li
• C. Al₂O₃
• D. Li⁺

Hint:

Always compare similar elements when checking periodic trends.

Answer 1

The Correct Option is B

Step 1: Acidity of group 15 hydrides increases down the group — option (A) correct.
Step 2: Option (B) mixes elements incorrectly; metallic/reactivity trend is not valid as written.
Step 3: Basic nature of oxides increases from Al₂O₃ to K₂O — option (C) correct.
Step 4: Ionic radius increases down the group — option (D) correct.