`{:("Column-I","Column-II"),((A)"74% occupancy of space",(p)"cubic close packing of identical spheres"),((B)"Coordination number =6",(q)"hexagonal close packing of identical spheres."),((C )"68% occupancy of space",(r)"body centered cubic packing of identical spheres."),((D)"Coordination number =12",(s)"simple cubic packing of identical spheres"),(,(t)"AB AB AB ....type of close packing of identical spheres"):}`

Explanation

To solve the matching question between Column-I and Column-II, we will analyze each entry in Column-I and find the corresponding entry in Column-II based on the properties of close packing of spheres.

### Step-by-Step Solution:

1. **Entry A: "74% occupancy of space"**
- The packing efficiency of both cubic close packing (CCP) and hexagonal close packing (HCP) is approximately 74%.
- Therefore, **A matches with P (cubic close packing of identical spheres) and Q (hexagonal close packing of identical spheres)**.

2. **Entry B: "Coordination number = 6"**
- In simple cubic packing, each sphere is in contact with 6 other spheres.
- Therefore, **B matches with S (simple cubic packing of identical spheres)**.

3. **Entry C: "68% occupancy of space"**
- The packing efficiency for body-centered cubic (BCC) packing is approximately 68%.
- Therefore, **C matches with R (body centered cubic packing of identical spheres)**.

4. **Entry D: "Coordination number = 12"**
- Both cubic close packing (CCP) and hexagonal close packing (HCP) have a coordination number of 12.
- Therefore, **D matches with P (cubic close packing of identical spheres), Q (hexagonal close packing of identical spheres), and T (AB AB AB ... type of close packing of identical spheres)**.

5. **Final Matching Results:**
- A → P, Q
- B → S
- C → R
- D → P, Q, T

### Summary of Matches:
- A: P, Q
- B: S
- C: R
- D: P, Q, T