The electron affinity values(in` KJ "mole"^(-1))` of three halogens x, y and z are respectively `-349, -333 and -325.` Then x, y and z respectively are 

Options

A. `F, Cl and Br`
B. `Cl , F and Br`
C. `Cl , Br and F`
D. `Br, Cl and F`

Answer

To determine which halogens correspond to the given electron affinity values of -349 kJ/mol, -333 kJ/mol, and -325 kJ/mol, we can analyze the trends in electron affinity among the halogens (Group 17 elements) which are fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

### Step-by-Step Solution:

1. **Identify the Halogens and Their Electron Affinities**:
- The halogens in order of their atomic number are:
- Fluorine (F)
- Chlorine (Cl)
- Bromine (Br)
- Iodine (I)
- The given electron affinity values are:
- x = -349 kJ/mol
- y = -333 kJ/mol
- z = -325 kJ/mol

2. **Understand the Trend in Electron Affinity**:
- As we move down the group from fluorine to iodine, the atomic size increases and the effective nuclear charge experienced by the outermost electrons decreases. This generally leads to a decrease in electron affinity.
- However, fluorine has a small atomic size which causes significant inter-electronic repulsion when an electron is added, resulting in a lower electron affinity compared to chlorine.

3. **Assign Electron Affinity Values to Halogens**:
- Based on the trend:
- Fluorine (F) has the lowest electron affinity due to inter-electronic repulsion, even though it is expected to have a high electron affinity due to its high electronegativity.
- Chlorine (Cl) has a higher electron affinity than fluorine.
- Bromine (Br) has the lowest electron affinity among these three.
- Therefore, we can assign:
- x = Chlorine (Cl) = -349 kJ/mol (highest electron affinity)
- y = Fluorine (F) = -333 kJ/mol
- z = Bromine (Br) = -325 kJ/mol (lowest electron affinity)

4. **Final Conclusion**:
- Thus, the halogens x, y, and z correspond to:
- x = Chlorine (Cl)
- y = Fluorine (F)
- z = Bromine (Br)

### Final Answer:
- x = Chlorine (Cl)
- y = Fluorine (F)
- z = Bromine (Br)