`NH_3` has got pyramidal structure. By replacement of `H` atom it forms `(CH_3)_3 N` and `(SiH_3)_3 N` molecules which are found to have different geometries.
Shape of `(SiH_3)_3 N` with respect to `N` is.

Options

A. Pyramidal
B. T-shaped
C. Trigonal planar
D. Tetrahedral

Explanation

To determine the shape of the molecule \((SiH_3)_3N\) (trisilyl amine) with respect to nitrogen (N), we can follow these steps:

### Step 1: Understand the Structure of Ammonia
Ammonia \((NH_3)\) has a pyramidal structure due to the presence of a lone pair of electrons on the nitrogen atom. The nitrogen atom is sp³ hybridized, and the lone pair pushes the hydrogen atoms down, creating a trigonal pyramidal shape.

**Hint:** Recall that the shape of a molecule can be influenced by lone pairs and the type of hybridization.

### Step 2: Analyze the Replacement of Hydrogen Atoms
When hydrogen atoms in ammonia are replaced by silyl groups \((SiH_3)\), we form \((SiH_3)_3N\). In this case, we need to consider how the bonding changes due to the presence of silicon atoms.

**Hint:** Consider how the bonding environment changes when substituents are added to the central atom.

### Step 3: Consider Back Bonding
In \((SiH_3)_3N\), back bonding occurs because silicon has vacant 3d orbitals, and nitrogen has a lone pair of electrons. The lone pair from nitrogen can interact with the vacant d-orbitals of silicon, which alters the geometry of the molecule.

**Hint:** Back bonding can significantly affect the geometry of a molecule. Think about how lone pairs can interact with orbitals of other atoms.

### Step 4: Determine the Geometry
Due to back bonding, the geometry of \((SiH_3)_3N\) changes from pyramidal to trigonal planar. The nitrogen atom is still bonded to three silicon atoms, but the interaction with the silicon's d-orbitals leads to a planar arrangement.

**Hint:** Visualize the geometry by considering the arrangement of atoms and the influence of lone pairs and bonding interactions.

### Step 5: Conclusion
Thus, the shape of \((SiH_3)_3N\) with respect to nitrogen is trigonal planar.

**Final Answer:** The shape of \((SiH_3)_3N\) with respect to nitrogen is **trigonal planar**.