Which of the following processes involves absorption of energy?

Options

A. `S(g)+e^(-) to S^(-)(g)`
B. `S^(-)+e^(-) to S^(2-)(g)`
C. `Cl(g)+e^(-) to Cl^(-)(g)`
D. none of these

Answer

To determine which of the following processes involves the absorption of energy, we need to analyze the nature of the reactions involved, particularly focusing on whether they are exothermic (release energy) or endothermic (absorb energy).

### Step-by-Step Solution:

1. **Understanding Exothermic and Endothermic Processes**:
- Exothermic processes release energy when a stable product is formed from reactants.
- Endothermic processes require energy input to convert reactants into products, especially when the products are less stable.

2. **Analyzing the Given Processes**:
- We need to look at the processes involving the addition of electrons to atoms or ions, as these often determine whether energy is absorbed or released.

3. **Example of Sulfur (S)**:
- Sulfur (S) has 16 electrons. When it gains one electron, it becomes S⁻ (17 electrons). This process is exothermic because S⁻ is relatively stable.
- However, if we try to add another electron to S⁻ to form S²⁻, we encounter a repulsion between the two negative charges. This repulsion means that energy must be supplied to overcome this barrier, making this process endothermic.

4. **Example of Chlorine (Cl)**:
- Chlorine (Cl) has 17 electrons. When it gains an electron, it becomes Cl⁻ (18 electrons). This process is exothermic because Cl⁻ achieves a stable noble gas configuration.

5. **Conclusion**:
- Among the processes discussed, the addition of an electron to S⁻ to form S²⁻ is the one that requires energy input, making it an endothermic process. Therefore, this process involves the absorption of energy.

### Final Answer:
The process that involves the absorption of energy is the addition of an electron to S⁻ to form S²⁻.