Question

The correct sequence of electron gain enthalpy of the elements listed below is
A. Ar 
B. Br 
C. F 
D. S 
Choose the most appropriate from the options given below:

• A. C > B > D > A
• B. A > D > B > C
• C. A > B > D > C
• D. D > C > B > A

Answer 1

The Correct Option is B

Understanding Electron Gain Enthalpy: Electron gain enthalpy is the amount of energy released when an electron is added to a neutral atom in the gaseous state to form a negative ion. Higher negative values indicate that an element releases more energy when gaining an electron, signifying higher electron affinity. 

Considering the Elements: We need to arrange Ar, Br, F, and S based on their electron gain enthalpy.

• Argon (Ar): As a noble gas, Argon has a complete octet, making its electron affinity negligible.
• Fluorine (F): Fluorine has a high electron affinity because it is one electron short of a complete octet, and it is known for having the highest electron affinity among halogens.
• Bromine (Br): Bromine, being another halogen, also exhibits high electron affinity but not as much as Fluorine. It has less electron gain enthalpy compared to Fluorine.
• Sulfur (S): Sulfur has a moderate electron affinity. It is less than that of halogens like Bromine or Fluorine.

Ranking based on Electron Gain Enthalpy: Considering the above information, the order of electron gain enthalpy from the most negative (most energy release) to the least is as follows:

• The least electron gain enthalpy is Argon because it is a noble gas.
• After Argon, Sulfur has lower electron gain enthalpy than Bromine.
• Bromine has lower electron gain enthalpy than Fluorine.
• Thus, the order is: \(A \gt D \gt B \gt C\)

Conclusion: Therefore, the correct sequence of electron gain enthalpy for the given elements is A > D > B > C.

Answer 2

\(Element\)	\(\Delta_{eg}\) \(H\) , \((\text{kJ/mol})\)
F	\(-333\)
S	\(-200\)
Br	\(-325\)
Ar	\(+96\)

Thus the correct answer is Option 2.