The correct answer is option 'C', which states that the complex [Cr(NH3)6]Cl3 is not an outer orbital complex. Let's understand why this statement is incorrect.

**Introduction to complex [Cr(NH3)6]Cl3:**
- The complex [Cr(NH3)6]Cl3 consists of a central chromium ion (Cr) surrounded by six ammonia molecules (NH3) as ligands and three chloride ions (Cl-) as counterions.
- The coordination number of the chromium ion is 6, as it is surrounded by six ligands.

**Explanation of the incorrect statement:**
c) The complex is an outer orbital complex.
- This statement is incorrect because the complex [Cr(NH3)6]Cl3 is an inner orbital complex, not an outer orbital complex.
- In outer orbital complexes, the d-orbitals of the central metal ion are involved in hybridization with the ligands, resulting in the formation of molecular orbitals that are mainly located outside the coordination sphere.
- However, in the complex [Cr(NH3)6]Cl3, the chromium ion has a partially filled d-orbital electronic configuration of d4.
- Since it has an odd number of electrons, it cannot form outer orbital complexes. Instead, it forms inner orbital complexes.
- In inner orbital complexes, the d-orbitals of the central metal ion are involved in hybridization with the ligands, resulting in the formation of molecular orbitals that are mainly located within the coordination sphere.

**Other options:**
a) The complex involves d2sp3 hybridisation and is octahedral in shape.
- This statement is correct. The complex [Cr(NH3)6]Cl3 involves d2sp3 hybridization, where the 3d, 4s, and three of the 4p orbitals of the chromium ion hybridize to form six sp3d2 hybrid orbitals.
- The complex is octahedral in shape, as it has six ligands arranged around the central chromium ion.

b) The complex is paramagnetic.
- This statement is correct. The complex [Cr(NH3)6]Cl3 has four unpaired electrons in its partially filled d-orbital, making it paramagnetic.
- Paramagnetic substances are attracted to a magnetic field due to the presence of unpaired electrons.

d) The complex gives a white precipitate with silver nitrate solution.
- This statement is correct. When [Cr(NH3)6]Cl3 is treated with silver nitrate (AgNO3) solution, a white precipitate of silver chloride (AgCl) is formed.
- This reaction occurs because the chloride ions (Cl-) from the complex react with the silver ions (Ag+) from silver nitrate to form insoluble silver chloride.