In which of the following processes energy is absorbed ?

Options

A. `Cl_((g))+e^(-)rarrCl_((g))^-`
B. `F_((g))^(-)+e^(-)rarrF_((g))^(2-)`
C. `Na_((g))^(+)+e^(-)rarrNa_((g))`
D. `Mg_((g))^(2+)+e^(-)rarrMg_((g))^+`

Answer

To determine in which of the following processes energy is absorbed, we need to analyze each process step by step.

### Step-by-Step Solution:

1. **Understanding Electron Affinity**:
- The first process is Cl + e⁻ → Cl⁻.
- In this reaction, a chlorine atom is gaining an electron to form a chloride ion.
- This process releases energy because the addition of an electron to a neutral atom typically results in a more stable configuration (completing its octet).
- **Conclusion**: Energy is released in this process.

2. **Analyzing Ionization Energy**:
- The second process is Na → Na⁺ + e⁻.
- Here, sodium is losing an electron to form a sodium ion.
- This requires energy input to remove the electron, which is known as ionization energy.
- **Conclusion**: Energy is absorbed in this process.

3. **Considering Electron Gain Enthalpy**:
- The third process is F⁻ + e⁻ → F²⁻.
- In this case, we are adding an electron to a fluoride ion.
- However, since F⁻ already has an extra electron, adding another electron would result in repulsion between the electrons.
- To overcome this repulsion, energy must be supplied.
- **Conclusion**: Energy is absorbed in this process.

4. **Examining the Second Ionization Energy**:
- The fourth process is Mg⁺ → Mg²⁺ + e⁻.
- This process involves removing an electron from a magnesium ion to form a magnesium ion with a higher positive charge.
- Similar to the second process, this requires energy input, known as the second ionization energy.
- **Conclusion**: Energy is absorbed in this process.

### Final Answer:
The processes in which energy is absorbed are:
- Na → Na⁺ + e⁻ (Ionization Energy)
- F⁻ + e⁻ → F²⁻ (Electron Gain Enthalpy)
- Mg⁺ → Mg²⁺ + e⁻ (Second Ionization Energy)