Match the type of crystal system given in List I with its description given in List II.
`{:("List I","List II"),("P. Monoclinic",1. a!= b != c " , " alpha != beta != gamma != 90^@),("Q. Tetragonal ", 2.a!= b != c" , " alpha = beta = gamma = 90^@),("R. Triclinic", 3.a!= b != c" , " alpha = gamma = 90^@ " , " beta != 90^@),("S. Rhombic", 4.a = b != c " , " alpha = beta = gamma = 90^@):}`

Options

A. `{:(P,Q,R,S),(3,4,2,1):}`
B. `{:(P,Q,R,S),(4,3,1,2):}`
C. `{:(P,Q,R,S),(3,4,1,2):}`
D. `{:(P,Q,R,S),(2,3,4,1):}`

Answer

To solve the problem of matching the crystal systems from List I with their descriptions in List II, we will analyze each crystal system and its corresponding parameters.

### Step-by-Step Solution:

1. **Monoclinic (P)**:
- In the monoclinic system, the three edge lengths are not equal (a ≠ b ≠ c), and two angles are equal to 90° (α = γ = 90°), while the third angle (β) is not equal to 90°.
- **Match**: Monoclinic (P) → 3 (a ≠ b ≠ c, α = γ = 90°, β ≠ 90°).

2. **Tetragonal (Q)**:
- In the tetragonal system, two edge lengths are equal (a = b) and the third edge length is different (c), with all angles equal to 90° (α = β = γ = 90°).
- **Match**: Tetragonal (Q) → 2 (a = b ≠ c, α = β = γ = 90°).

3. **Triclinic (R)**:
- In the triclinic system, none of the edge lengths are equal (a ≠ b ≠ c), and none of the angles are equal (α ≠ β ≠ γ), with no angle being 90°.
- **Match**: Triclinic (R) → 1 (a ≠ b ≠ c, α ≠ β ≠ γ ≠ 90°).

4. **Rhombic (S)**:
- In the rhombic (orthorhombic) system, all three edge lengths are different (a ≠ b ≠ c), and all angles are equal to 90° (α = β = γ = 90°).
- **Match**: Rhombic (S) → 4 (a ≠ b ≠ c, α = β = γ = 90°).

### Final Matches:
- P (Monoclinic) → 3
- Q (Tetragonal) → 2
- R (Triclinic) → 1
- S (Rhombic) → 4