4. (18 pts) Assume a Sr (strontium) single crystal (FCC) unit cell with a conventional unit cell side length of 0.608 nm and a 4-point basis. In an x-ray diffraction measurement (x-ray wavelength = 0.154nm) calculate the diffraction angle, 20, for the following diffraction peaks. (Assume that the (hkl) indices below are with respect to the reciprocal lattice of a simple cubic lattice with a unit cell side length of 0.608nm.) a. (110) b. (111) C. (211) d. (311) e. (420) e