Assertion : In `NH_(3), N "is " sp^(3)` hybridised but bond angle is `107^(@)`.
Reason : Shape of `NH_(3)` molecule is trigonal pyramidal.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason in not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Analyze the Assertion
The assertion states that in NH₃ (ammonia), nitrogen (N) is sp³ hybridized and that the bond angle is 107°.

- **Hybridization of Nitrogen in NH₃**: In ammonia, nitrogen has one lone pair and three bonding pairs (one for each hydrogen atom). The hybridization of nitrogen in NH₃ is indeed sp³, as it involves mixing one s orbital and three p orbitals to form four equivalent sp³ hybrid orbitals.
- **Bond Angle**: The ideal bond angle for a perfect tetrahedral arrangement (which is what sp³ hybridization would suggest) is 109.5°. However, due to the presence of a lone pair, the bond angle is slightly reduced to 107°.

### Conclusion for Step 1:
The assertion is correct: nitrogen in NH₃ is sp³ hybridized, and the bond angle is 107°.

### Step 2: Analyze the Reason
The reason states that the shape of the NH₃ molecule is trigonal pyramidal.

- **Shape of NH₃**: The presence of the lone pair on nitrogen causes the shape of the molecule to be trigonal pyramidal rather than tetrahedral. The three hydrogen atoms form the base of the pyramid, and the lone pair occupies the apex, which indeed results in a trigonal pyramidal shape.

### Conclusion for Step 2:
The reason is also correct: the shape of NH₃ is trigonal pyramidal.

### Step 3: Determine the Relationship
Now we need to determine if the reason correctly explains the assertion.

- The reduction in bond angle from 109.5° to 107° is indeed due to the presence of the lone pair, which affects the geometry of the molecule, leading to a trigonal pyramidal shape. Thus, the reason does explain the assertion.

### Final Conclusion:
Both the assertion and the reason are true, and the reason correctly explains the assertion. Therefore, the answer to the question is that both the assertion and reason are correct, and the reason is a correct explanation of the assertion.

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