In the following questions, a statement of assertion (A) is followed by a statement of reason (R )
A: bond angle of `BF_(3) and NF_(3)` are different.
R : Both the molecules are having different shape

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2)
C. If Assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Reason are false statements , then mark (4).

Answer

To solve the question regarding the bond angles of BF3 and NF3 and their shapes, we can follow these steps:

### Step 1: Identify the Molecular Structures
- **BF3 (Boron Trifluoride)**: Boron is in group 13 and has 3 valence electrons. It forms three bonds with fluorine atoms.
- **NF3 (Nitrogen Trifluoride)**: Nitrogen is in group 15 and has 5 valence electrons. It forms three bonds with fluorine atoms and has one lone pair of electrons.

**Hint**: Consider the group number of the central atom to determine the number of valence electrons.

### Step 2: Determine the Hybridization
- For **BF3**:
- Steric number = Number of bond pairs + Number of lone pairs = 3 (bond pairs) + 0 (lone pairs) = 3.
- Hybridization = sp².

- For **NF3**:
- Steric number = 3 (bond pairs) + 1 (lone pair) = 4.
- Hybridization = sp³.

**Hint**: Use the steric number to find the hybridization of the molecule.

### Step 3: Analyze the Shapes of the Molecules
- **BF3** has a trigonal planar shape due to sp² hybridization.
- **NF3** has a pyramidal shape due to sp³ hybridization and the presence of a lone pair.

**Hint**: The shape of the molecule can be inferred from its hybridization and the presence of lone pairs.

### Step 4: Determine the Bond Angles
- In **BF3**, the bond angle is approximately 120 degrees.
- In **NF3**, due to the lone pair repulsion, the bond angle is reduced to about 101.9 degrees.

**Hint**: Remember that lone pairs can affect bond angles by causing repulsion.

### Step 5: Conclusion
- The assertion (A) states that the bond angles of BF3 and NF3 are different, which is true.
- The reason (R) states that both molecules have different shapes, which is also true.
- Since both statements are true and the reason correctly explains the assertion, the answer is that both assertion and reason are true, and the reason is the correct explanation of the assertion.

**Final Answer**: Both assertion and reason are true, and the reason is the correct explanation of the assertion.