Question

the correct order of negative electron gain enthalpy is
1)S<O
2)O<F
3)CI<F
4)F<BR

PLEASE ANSWER ✨

Answer 1

$\underline{\large\bf{\mathfrak{Hello!}}}$

⭐ Electron Gain Enthalpy ⭐

The amount of energy associated with the gain of electrons by the isolated gaseous atom".

As, we know that the Electron Gain Enthalpy mostly increases(in negative value) from left to right in a period and decreases from top to bottom in group.

But there are some exceptions in this;
As, electron gain enthalpy of S and Cl is great than O and F in a group because in O and F electron is added to n = 2 quantum number. Due to small size the interelectronic repulsion increases causing the decrease in electron gain enthalpy value.

Now, the value of electron gain enthalpy of elements given in the respective question;

O -› -141
F -› -328
S -› 200
Cl -› 349
Br -› -325

So, after seeing everything we can conclude that option (2) is the correct answer.
As, F have greater negative electron gain enthalpy than O.

$\bf{\mathfrak{Hope \: this \: helps...:)}}$