(A): Electron gain enthalpy of noble gases is very less (R): Atoms of noble gases have completely filled orbitals 

Options

A. Both A & R are true, R is the correct explanation of A
B. Both A & R are true, R is not correct explanation of A
C. A is true, R is false
D. A is false, R is true

Answer

To solve the question regarding the electron gain enthalpy of noble gases and their electronic configuration, we can break it down into clear steps:

### Step-by-Step Solution:

1. **Understanding Electron Gain Enthalpy**:
- Electron gain enthalpy refers to the energy change when an electron is added to a neutral atom in the gaseous state. For most elements, this value is negative, indicating that energy is released when an electron is added.

2. **Noble Gases and Their Electron Gain Enthalpy**:
- Noble gases (Group 18 elements: Helium, Neon, Argon, Krypton, Xenon, Radon) have a unique characteristic: they have a complete octet in their outermost electron shell (ns² np⁶ configuration). This stability means they are less likely to gain additional electrons.

3. **Positive Values of Electron Gain Enthalpy**:
- For noble gases, the electron gain enthalpy values are either very low or positive. This indicates that adding an electron does not favorably occur because the noble gases already possess a stable electronic configuration.

4. **Reason for Low Electron Gain Enthalpy**:
- The reason for the low or positive electron gain enthalpy is that noble gases have completely filled orbitals, making them stable. They have no tendency to attract additional electrons, which would disrupt their stable configuration.

5. **Conclusion**:
- Therefore, the statement (A) "Electron gain enthalpy of noble gases is very less" is false because it is positive, while the reason (R) "Atoms of noble gases have completely filled orbitals" is true. Thus, the correct conclusion is that (A) is false and (R) is true.

### Final Answer:
- (A) is false, (R) is true. Therefore, the correct option is D.