Which of the following statement is correct?

Options

A. The magnitude of the second electron ffinity of sulphur is greater than that of oxygen
B. The magnitude of the second electron affinity of sulphur is less than that of oxygen
C. the first electron affinities of bromine and iodine are approximately the same
D. The first electron affinity of fluorine is greater than that of chlorine

Answer

To solve the question regarding the correct statement about the second electron gain enthalpy of oxygen and sulfur, we can follow these steps:

### Step 1: Understand Electron Gain Enthalpy
Electron gain enthalpy refers to the energy change when an electron is added to a neutral atom to form an anion. The first electron gain enthalpy is usually negative because energy is released when an electron is added. However, the second electron gain enthalpy can be positive, especially when adding an electron to an already negatively charged ion.

**Hint:** Remember that adding an electron to a negatively charged ion leads to repulsion between electrons.

### Step 2: Analyze Oxygen (O)
When oxygen (O) gains its first electron, it forms O⁻. The addition of a second electron to O⁻ results in O²⁻. Since both electrons are negatively charged, they repel each other. This repulsion requires energy to overcome, making the second electron gain enthalpy for oxygen positive.

**Hint:** Consider the charge of the ion when adding another electron.

### Step 3: Analyze Sulfur (S)
Similarly, when sulfur (S) gains its first electron, it forms S⁻. The addition of a second electron to S⁻ results in S²⁻. Just like with oxygen, the repulsion between the two negative charges means that the second electron gain enthalpy for sulfur is also positive.

**Hint:** Compare the size and electron configurations of sulfur and oxygen.

### Step 4: Compare the Second Electron Gain Enthalpies
Now, we need to compare the second electron gain enthalpy of oxygen and sulfur. Oxygen has a smaller atomic radius compared to sulfur, which means that the electrons in oxygen are closer to the nucleus and experience greater repulsion when a second electron is added. Therefore, more energy is required to add the second electron to oxygen than to sulfur.

**Hint:** Think about how atomic size affects electron-electron repulsions.

### Step 5: Conclusion
Based on the analysis, we conclude that the magnitude of the second electron gain enthalpy of oxygen is greater than that of sulfur. Therefore, the correct statement is that the second electron gain enthalpy of sulfur is less than that of oxygen.

**Final Answer:** The correct statement is that the magnitude of the second electron affinity of sulfur is less than that of oxygen.