Question

Which one of the following arrangements represents the correct order of electron gain enthalpy (with negative sign) of the given atomic species?

• A. S < O < Cl < F
• B. Cl < F < S < O
• C. F < Cl < O < S
• D. O < S < F < Cl

Hint:

Small atomic size increases electron–electron repulsion, reducing electron gain enthalpy.

Answer 1

The Correct Option is D

Step 1: Electron gain enthalpy becomes more negative across a period.
Step 2: Due to small size, oxygen and fluorine have less negative values than expected.
Step 3: Correct order (most negative last): \[ \text{O} < \text{S} < \text{F} < \text{Cl} \]