question_answer 18)

An element with molar mass 2.7 x 10-2 kg mol-1 forms a cubic unit cell with edge length 405pm. If its density is 2.7 x 103 kg m-3, what is the nature of the cubic unit cell?  

Answer:

a = 405 pm = 405 x 10?12 m, M = 27 x 10?2 kg mol?1 NA = 6022 x 1023 mot?1, d = 27 x 103 kg m?3 Now, = 4 Since, No. of atoms per unit cell are 4, so it must be a face centred cubic unit cell.