$A$ solid is made of two elements $X$ and $Y$. Atoms of $X$ are in $FCC$ arrangement and $Y$ atoms occupy all tetrahedral sites. What is the possible formula of the compound?

Explain three-dimensional close packing from two-dimensional hexagonal close packing. Explain the formation of face-centered cubic $(FCC)$ unit cell and hexagonal close packing $(HCP)$ in three dimensions.

$A$ compound is formed by elements $A$ and $B$ which crystallizes in a $CCP$ structure. Atoms of $A$ are at the corners and atoms of $B$ are at the face centers. If two atoms of $A$ are missing from the unit cell,what is the molecular formula of the compound?

$A$ crystalline solid $XY_3$ has a $ccp$ arrangement for its element $Y$. $X$ occupies:

The volume of the $HCP$ unit cell is

In a solid,oxide ions are arranged in $HCP$. Cations $A$ occupy one-sixth of $THV$ and cations $B$ occupy one-third of the $OHV$. The empirical formula of the compound is