20. A unit cell has the dimensions a = 4 A, b= 6 A, c = 8 A, x = ß = 90°, y = 120°. Determine: a) a*, b*, and c* for the reciprocal cell. b) The volume of the real and reciprocal unit cells. c) The spacing between the (210) planes. d) The Bragg angle 0 for reflection from the above planes.

3. Draw the lattice for Pt which crystallized in a cubic unit cell with 4 equivalent Pt atoms.

Calculate the volume in Å3 of each of the following types of cubic unit cells if it is composed of atoms with an atomic radius of 1.61 Å. a). primitive Express the volume in cubic angstroms to three significant digits.   b).face-centered cubic Express the volume in cubic angstroms to three significant digits.

The height of a unit cell in an HCP structure was given as 5.2368Å. Determine the edge length in a unit cell.