Which d-orbital is involved in ` sp^(3) d` hydridisation and why ?

Explanation

To determine which d-orbital is involved in sp³d hybridization, we can follow these steps:

### Step 1: Understand Hybridization
Hybridization involves the mixing of atomic orbitals to form new hybrid orbitals. In sp³d hybridization, one s orbital, three p orbitals, and one d orbital combine to form five equivalent hybrid orbitals.

### Step 2: Identify the Orbitals
In sp³d hybridization, the involved orbitals are:
- 1 s orbital
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