Powder specimens of two different monoatomic cubic crystals are analysed with X-ray diffraction (wavelength 0.150 nm). It is known that one sample is nio- bium (Nb), which crystallises in a bcc structure, and the other is palladium (Pd), which crystallises in the fcc structure. Sample A Sample B 20 20 39.110 37.37 45.47 53.87 66.27 67.40 79.72 79.68 (a) Determine the reflections hk/ that give rise to peaks in the diffraction pat- tern for bcc and fcc, for all reflections up to 311. (b) Hence, using the experimental data above, identify which sample is Nb and which sample is Pd, and determine their lattice parameters