Which of the following order of molecular force of attraction among given species is incorect ?

Options

A. `HI gt HBr gt Cl_(2)`
B. `CH_(3)Cl gt C Cl_(4) gt CH_(4)`
C. n-pentane `gt` iso-pentane `gt` neo-pentane
D. `OH_(2) gt O (CH_(3))_(2) gt OB r_(2)`

Explanation

To solve the question regarding the incorrect order of molecular forces of attraction among the given species, we will analyze each option step-by-step.

### Step-by-Step Solution:

1. **Understanding Molecular Forces of Attraction**:
- Molecular forces of attraction include hydrogen bonding, dipole-dipole interactions, and London dispersion forces. The strength of these forces depends on the molecular structure, polarity, and size of the molecules involved.

2. **Analyzing Option A (HI > HBr > Cl2)**:
- **HI**: Hydrogen iodide has a polar covalent bond and a larger atomic size (iodine) leading to stronger dipole-dipole interactions.
- **HBr**: Hydrogen bromide is also polar, but bromine is smaller than iodine, leading to weaker interactions compared to HI.
- **Cl2**: Chlorine is a non-polar molecule with London dispersion forces, which are weaker than the dipole-dipole interactions in HI and HBr.
- **Conclusion**: The order HI > HBr > Cl2 is correct.

3. **Analyzing Option B (CH3Cl > CCl4 > CH4)**:
- **CH3Cl**: Methyl chloride is polar due to the C-Cl bond, leading to stronger dipole-dipole interactions.
- **CCl4**: Carbon tetrachloride is non-polar, but has a larger molecular size than CH4, leading to stronger London dispersion forces.
- **CH4**: Methane is non-polar and has the weakest forces of attraction among the three.
- **Conclusion**: The order CH3Cl > CCl4 > CH4 is incorrect because CCl4 should have stronger forces than CH4 due to its larger size.

4. **Analyzing Option C (n-pentane > isopentane > neopentane)**:
- **n-Pentane**: A straight-chain hydrocarbon with a larger surface area, leading to stronger London dispersion forces.
- **Isopentane**: A branched isomer with less surface area than n-pentane, resulting in weaker forces.
- **Neopentane**: Highly branched, leading to the least surface area and weakest forces.
- **Conclusion**: The order n-pentane > isopentane > neopentane is correct.

5. **Analyzing Option D (H2O > OBr2 > O(CH3)2)**:
- **H2O**: Water has strong hydrogen bonding, making it the strongest in terms of molecular forces.
- **OBr2**: Oxygen dibromide has dipole-dipole interactions and a larger molecular mass than O(CH3)2, leading to stronger forces than O(CH3)2.
- **O(CH3)2**: Dimethyl ether has weaker dipole-dipole interactions compared to OBr2.
- **Conclusion**: The order H2O > OBr2 > O(CH3)2 is correct.

### Final Conclusion:
The incorrect order of molecular forces of attraction is found in **Option B (CH3Cl > CCl4 > CH4)**.