Assertion : Geometry of `IC l_(3)` is tetrahedral.
Reason : Its shape is T-shape, due to the presence of two lone pairs.

Options

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

Answer

### Step-by-Step Solution:

1. **Identify the Compound**: The compound in question is ICl3 (Iodine trichloride).

2. **Determine the Valence Electrons**:
- Iodine (I) has 7 valence electrons.
- Each Chlorine (Cl) has 7 valence electrons, and there are 3 Cl atoms contributing a total of 21 electrons.
- Total valence electrons = 7 (from I) + 21 (from 3 Cl) = 28 valence electrons.

3. **Draw the Lewis Structure**:
- Iodine is the central atom and forms single bonds with three chlorine atoms.
- Each bond uses 2 electrons, so 3 bonds use 6 electrons.
- Remaining electrons = 28 - 6 = 22 electrons.
- These remaining electrons will be placed as lone pairs on the central iodine atom.

4. **Count Lone Pairs**:
- After forming 3 bonds, there are 4 electrons left, which means there are 2 lone pairs on the iodine atom.

5. **Determine the Steric Number**:
- The steric number (Z) is the sum of bond pairs and lone pairs.
- In ICl3, there are 3 bond pairs and 2 lone pairs, so Z = 3 + 2 = 5.

6. **Identify Hybridization**:
- With a steric number of 5, the hybridization is sp³d.

7. **Determine the Geometry**:
- The geometry for a steric number of 5 is trigonal bipyramidal.

8. **Determine the Molecular Shape**:
- In the trigonal bipyramidal geometry, the two lone pairs will occupy the equatorial positions to minimize repulsion, resulting in a T-shaped molecular geometry for ICl3.

9. **Evaluate the Assertion and Reason**:
- **Assertion**: "Geometry of ICl3 is tetrahedral" - This is **false**.
- **Reason**: "Its shape is T-shape, due to the presence of two lone pairs" - This is **true**.

10. **Conclusion**:
- The assertion is false, but the reason is true. Therefore, the correct option is that the assertion is false and the reason is true.