JEE Chemistry 2024 Question with Solution

Given: The question asks the reason for the anomalous behavior of oxygen.

Find: Which property combination correctly explains this behavior.

Oxygen shows anomalous behavior compared to other elements of its group because it has small size and high electronegativity.

• Its small atomic size leads to strong attraction between the nucleus and valence electrons.
• Its high electronegativity makes it attract shared electrons strongly and form highly polar covalent bonds.
• These properties make oxygen differ from heavier group members such as sulfur and selenium.

Therefore, the correct option is C: Small size and high electronegativity.

Given: Oxygen is a second-period element and is being compared with other elements of its group.

Find: The pair of properties responsible for its anomalous behavior.

From the solution text:

1. Small Size: Oxygen is a very small atom because it belongs to the second period.
2. The small size causes a stronger nuclear pull on valence electrons.
3. High Electronegativity: Oxygen is highly electronegative, second only to fluorine.
4. Because of this, oxygen attracts bonding electrons strongly and shows distinctive chemical behavior.
5. Hence, oxygen forms compounds and shows reactivity different from sulfur, selenium, and other heavier congeners.

The options with large size are incorrect because oxygen is not large. The option with low electronegativity is incorrect because oxygen is highly electronegative.

Therefore, the correct answer is Small size and high electronegativity, that is, option C.