If the number of tetrahedral voids in a crystal lattice is $N$,then the number of close-packed spheres will be ..........

The number of tetrahedral voids per unit $HCP$ cell is

Assertion : In close packing of spheres,a tetrahedral void is surrounded by four spheres whereas an octahedral void is surrounded by six spheres.
Reason : $A$ tetrahedral void has a tetrahedral shape whereas an octahedral void has an octahedral shape.

In an ionic solid, anions $(B)$ are arranged in an $hcp$ array and cations $(A)$ occupy $1/2$ of the tetrahedral voids. What is the formula of the ionic compound?

The number of octahedral and tetrahedral holes respectively present in a hexagonal close packed $(hcp)$ crystal of $X$ atoms are

$A$ two-dimensional solid pattern formed by two different atoms $X$ and $Y$ is shown below. The black and white squares represent atoms $X$ and $Y,$ respectively. The simplest formula for the compound based on the unit cell from the pattern is