TG EAMCET 3 May 2025 Shift 1 Paper

Let's determine the electron gain enthalpies for the given elements based on periodic trends and known values. Electron gain enthalpy ( ∆egH ) is the energy change when an electron is added to a neutral gaseous atom. A more negative value indicates a greater tendency to accept an electron (more exothermic process).

General Trends:
Group 17 (Halogens) have the most negative electron gain enthalpies. Among halogens, chlorine (CI) generally has a more negative electron gain enthalpy than fluorine (F) because F's small size leads to significant interelectronic repulsion when an incoming electron is added, making it less favorable than Cl .

Chlorine (CI): Expect a very large negative value.
Fluorine (F): Expect a large negative value, but slightly less negative than Cl .
Group 16 (Chalcogens) also have negative electron gain enthalpies. Similar to halogens, sulfur ( S ) generally has a more negative electron gain enthalpy than oxygen ( 0 ) due to 0 's small size and resulting interelectronic repulsion.

Sulfur (S): Expect a negative value.
Oxygen (0): Expect a negative value, but less negative than S .
Let's examine the provided values in List-II:
I. −200kJmol−1
II. −349kJmol−1
III. −141kJmol−1
IV. −328kJmol−1
V. +48kJmol−1 (This is a positive value, meaning energy is required to add an electron, which is characteristic of elements like noble gases or alkaline earth metals, but not O,F,Cl,S for the first electron gain).

Now let's match the elements:
Chlorine (CI): It is known to have the most negative electron gain enthalpy among all elements. Among the given negative values, −349kJmol−1 is the most negative.
So, C(Cl)⟶ II (−349kJmol−1).
Fluorine (F): It has a very large negative electron gain enthalpy, but due to its smaller size and interelectronic repulsion, it's slightly less exothermic than Cl . The second most negative value is −328kJmol‌−1.

So, B(F)⟶ IV (−328kJmol−1).
Sulfur (S): Belonging to Group 16, its electron gain enthalpy is exothermic, and it should be more negative than Oxygen. Comparing the remaining negative values ( -200 and -141 ), −200kJmol‌−1 is more negative.

So, D(S)⟶I(−200kJmolI−1).
Oxygen (0): Also in Group 16, its small size leads to interelectronic repulsion, making its electron gain enthalpy less negative (less exothermic) than that of Sulfur. The remaining negative value is -141 kJmol−1.

So, A(0)⟶ III (−141kJmolb−1)..
Let's summarize the matching:
A(0)⟶III(−141kJmol−1)
B (F) → IV (−328kJmol−1)
C(Cl)⟶II(−349kJmol−1)
D(S)⟶I(−200kJmol−1)
Comparing this with the given options:
Option C: A-III, B-IV, C-II, D-I
This matches our derived assignments.
The final answer is □ Option C