A unit cell is a The smallest group of atoms which when regu

A unit cell is (a) The smallest group of atoms which when regularly repealed forms the crystal (b) A group of atoms which form a cubic arrangement (c) A unit cube containing the smallest number of atoms (d) The smallest group of atoms which will diffract X-rays. Crystalline materials atoms: (a) are pack in periodic (b) have no periodic packing (c) tend to be densely packed (d) a, c ATOMIC PACKING FACTOR (Volume of atoms in unit cell/Volume of unit cell) tor HCP crystal structure (a) 0.52 (b) 0.68 (c) 0.74 (d) 1 Single crystal is Anisotropic: (a) True (b) False (c) Depends on type of unit cell (d) None Polycrystalline material are anisotropic: (a) True (b) False (c) If grains are textured (d) If grains are randomly oriented

Solution

8. a. Unit cell is smallest group of atoms which when regularly repeated formed the crystal

9. d crystalline material atoms are pack in periodic and densely packed

10. c. Atomic packing factor of HCP structure is 0.74

11.a

12. c