`PCl_(5)` is an example of a molecule having `sp^(3)d`-hybridisation. Three out of the orbitals in `sp_(x)p_(y)`-hybridisation while remaining two have `p_(x)d_(x^(2))`-hybridisation. If P-atom is attached to substitutuents differ in electronegativity, as in `PCl_(x)F_(5-x)`, then it is has been experimently observed that the more electronegativity substituent occupies the axial position of t.b.p geometry.
Q. The highest `H-C-H` bond angle present in :

Answer

To determine the highest H-C-H bond angle among the given molecules, we need to analyze the structures and the influence of electronegativity on the bond angles.

### Step 1: Identify the Molecules
The molecules we are considering are:
1. CH₄ (Methane)
2. CH₃F (Fluoromethane)
3. CH₂F₂ (Difluoromethane)
4. CHCl₃ (Chloroform)

### Step 2: Understand the Hybridization and Geometry
- **CH₄**: The carbon atom is sp³ hybridized, leading to a tetrahedral geometry with bond angles of approximately 109.5°.
- **CH₃F**: The presence of a more electronegative fluorine atom distorts the tetrahedral geometry, resulting in a bond angle slightly less than 109.5°.
- **CH₂F₂**: With two fluorine atoms, the bond angles are further reduced due to the increased electronegativity of the substituents.
- **CHCl₃**: Chlorine is less electronegative than fluorine, which means the bond angles will be larger than in CH₂F₂ but still less than in CH₄.

### Step 3: Compare the Bond Angles
- **CH₄** has the highest bond angle (109.5°) because it has only hydrogen atoms, which are less electronegative than fluorine or chlorine.
- **CH₃F** has a bond angle slightly less than 109.5° due to the presence of fluorine.
- **CH₂F₂** will have even smaller bond angles due to the two fluorine atoms.
- **CHCl₃** will have bond angles larger than CH₂F₂ but smaller than CH₄.

### Conclusion
The highest H-C-H bond angle is found in **CH₄ (Methane)**, which is approximately 109.5°.

### Final Answer
The highest H-C-H bond angle is present in **CH₄**.

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