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Question
Which of the following statement is not true about the hexagonal close packing?
Options
The coordination number is 12.
It has 74% packing efficiency.
Tetrahedral voids of the second layer are covered by the spheres of the third layer.
In this arrangement spheres of the fourth layer are exactly aligned with those of the first layer.
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Solution
In this arrangement spheres of the fourth layer are exactly aligned with those of the first layer.
Explanation:
Hexagonal close packing can be arranged by two layers
A and B one over another which can be diagrammatically represented as
Here, we can see easily that 1st layer and 4th layer are not exactly aligned. Thus, statement (iv) is not correct while other statements (i), (ii) and (iii) are true.
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