What are triangular voids?Is these voids are formed 1D?formula for finding these voids

Q.

Which of the following is not true about the voids formed in 3 dimensional hexagonal close packed structure ?

(a) A tetrehedral void is formed when a sphere of the second layer is present above triangular void in the first layer

(b) All the triangular voids are not covered by the spheres of the second layer

(c) Tetrahedral voids are formed when the triangular voids in the second layer lie above the triangular voids in the first layer and the triangulare shapes of these voids do not overlap

(d) Octahedral voids are formed when the triagular voids in th second layer exactly overlap with similar voids in the first layer

Q. A compound forms hexagonal close-packed structure. What is the total number of voids in 0.5 many of these are tetrahedral voids?

Q. A compound forms hexagonal close-packed structure. What is the total number of voids in $0.5mol$ of it.How many of these are tetrahedral voids?

Q.

A compound forms hexagonal close-packed structure. What is the total number of voids in 0.5 mol of it? How many of these are tetrahedral voids?