Question

Which of the following statements is not true about 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 spheres of the third layer.
(d) In this arrangement spheres of the fourth layer are exactly aligned with those of the first.

Answer 1

(d) In this arrangement spheres of the fourth layer are exactly aligned with those of the first.

In hcp arrangement ABAB type and not ABC ABC type. Hence (d) is not true.