Match List I with List II
| List I | List II |
| A. Triclinic | I. \(BaSO_4\) |
| B. Monoclinic | II. \(K_2Cr_2O_7\) |
| C. Rhombohedral | III. \(Na_2SO_4.10H_2O\) |
| D. Orthorhombic | IV. \(CaCO_3\) |
Choose the correct answers from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → A-II, B-III, C-IV, D-I
The seven crystal systems differ in their unit cell edges (a, b, c) and angles (α, β, γ). Each system has typical examples.
(A) Triclinic — This matches (II) K2Cr2O7. In a triclinic cell a ≠ b ≠ c and α ≠ β ≠ γ ≠ 90°; \( \ce{K2Cr2O7} \), \( \ce{CuSO4.5H2O} \) and \( \ce{H3BO3} \) are examples.
(B) Monoclinic — This matches (III) Na2SO4.10H2O. In a monoclinic cell a ≠ b ≠ c, α = γ = 90° and β ≠ 90°; Glauber’s salt and monoclinic sulphur are examples.
(C) Rhombohedral — This matches (IV) CaCO3. In a rhombohedral cell a = b = c and α = β = γ ≠ 90°; calcite (\( \ce{CaCO3} \)) and cinnabar (HgS) are examples.
(D) Orthorhombic — This matches (I) BaSO4. In an orthorhombic cell a ≠ b ≠ c and α = β = γ = 90°; \( \ce{BaSO4} \), \( \ce{KNO3} \) and rhombic sulphur are examples.
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.