CUET Preparation Today
Match List - I with List - II.
Choose the correct answer from the options given below: |
(A)-(IV), (B)-(I), (C)-(III), (D)-(II) (A)-(IV), (B)-(III), (C)-(II), (D)-(I) (A)-(I), (B)-(III), (C)-(IV), (D)-(II) (A)-(I), (B)-(II), (C)-(IV), (D)-(III) |
(A)-(IV), (B)-(III), (C)-(II), (D)-(I) |
The correct answer is Option 2. (A)-(IV), (B)-(III), (C)-(II), (D)-(I).
Crystals are solid materials whose constituents (atoms, ions, or molecules) are arranged in a highly ordered structure, forming a crystal lattice. The arrangement and dimensions of the unit cell, the smallest repeating unit of the crystal lattice, define the crystal system. There are seven crystal systems, but we'll focus on four of them: cubic, tetragonal, orthorhombic, and hexagonal. A cubic crystal system has unit cells where all three sides (a, b, c) are equal in length and all angles are right angles (90°). Conditions: \( a = b = c \) Angles: 90°. Examples: Sodium chloride (NaCl), diamond, and metals like gold and silver. Properties: Cubic crystals exhibit high symmetry, which often leads to isotropic properties (the same in all directions). B. Tetragonal In a tetragonal crystal system, two sides are equal in length, while the third side differs. The angles are all right angles (90°). Conditions: \( a = b \neq c \) Angles: 90°. Examples: Tin (β-tin) and some forms of quartz. Properties: Tetragonal crystals have a lower symmetry compared to cubic crystals but still retain some regularity in their structure. C. Orthorhombic The orthorhombic system has all three sides of different lengths, and all angles are right angles (90°). Conditions: \( a \neq b \neq c \) Angles: 90°. Examples: Sulfur, olivine, and many types of crystals in the mineral kingdom. Properties: This system allows for more variability in crystal shapes compared to cubic and tetragonal systems. D. Hexagonal The hexagonal system features a unit cell where two sides are equal, and the angles between the sides are 120° for the base, while the height differs. Conditions: \( a = b \neq c \) Angles: 120° between a and b; 90° between c and a/b. Examples: Graphite, quartz, and some metals like titanium Conclusion The correct matching reflects the fundamental properties of each crystal system. Understanding these properties is crucial in materials science, geology, and various applications in chemistry and physics. The arrangement of atoms in these systems influences the physical and chemical properties of materials, such as their melting points, hardness, and optical behaviors. |
