question_answer 75)

  Which of the following statement is not true about the hexagonal close packing? (a) The coordination number is 12 (b) It has 74% packing efficiency (c) Tetrahedral voids of the second layer are covered by the spheres of the third layer (d) In this arrangement spheres of the fourth layer are exactly aligned with those of the first layer

Answer:

                  (d) Hexagonal close packing can be arranging by two layers A and B one over another which can be diagramatically represented as Here, we can see easily that 1st layer and 4th layer are not exactly aligned. Thus, statement (d) is not correct while other statements (a), (b) and (c) are true.