Match List I with List II
| LIST I | LIST II |
| A. Cubic | I. Graphite |
| B. Triclinic | II. White tin |
| C. Hexagonal | III. Zinc blende |
| D. Tetragonal | IV. Potassium dichromate |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → A-III, B-IV, C-I, D-II
(A) Cubic (a = b = c, all angles 90°) — This matches (III) Zinc blende (also NaCl, Cu).
(B) Triclinic (a ≠ b ≠ c, all angles different from 90°) — This matches (IV) Potassium dichromate (\( \ce{K2Cr2O7} \), also \( \ce{CuSO4} \).\( \ce{5H2O} \)).
(C) Hexagonal (a = b ≠ c; α = β = 90°, γ = 120°) — This matches (I) Graphite (also ZnO, CdS).
(D) Tetragonal (a = b ≠ c, all angles 90°) — This matches (II) White tin (also \( \ce{SnO2} \), \( \ce{TiO2} \)).
Shortcut: (A)-(III) is true only in Option (4).
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Primitive and Centred Unit Cells – Table 1.3: Seven Primitive Unit Cells and their Possible Variations as Centred Unit Cells
| Crystal system | Possible variations | Axial distances or edge lengths | Axial angles | Examples |
|---|---|---|---|---|
| Cubic | Primitive, Body-centred, Face-centred | a = b = c | α = β = γ = 90° | NaCl, Zinc blende, Cu |
| Tetragonal | Primitive, Body-centred | a = b ≠ c | α = β = γ = 90° | White tin, SnO2, TiO2, CaSO4 |
| Orthorhombic | Primitive, Body-centred, Face-centred, End-centred | a ≠ b ≠ c | α = β = γ = 90° | Rhombic sulphur, KNO3, BaSO4 |
| Hexagonal | Primitive | a = b ≠ c | α = β = 90°, γ = 120° | Graphite, ZnO, CdS |
| Rhombohedral or Trigonal | Primitive | a = b = c | α = β = γ ≠ 90° | Calcite (CaCO3), HgS (cinnabar) |
| Monoclinic | Primitive, End-centred | a ≠ b ≠ c | α = γ = 90°, β ≠ 90° | Monoclinic sulphur, Na2SO4.10H2O |
| Triclinic | Primitive | a ≠ b ≠ c | α ≠ β ≠ γ ≠ 90° | K2Cr2O7, CuSO4.5H2O, H3BO3 |