The interionic distance for $Cesium$ $chloride$ $(CsCl)$ crystal will be (where $a$ is the edge length of the unit cell):

Which of the following expressions is correct in the case of a $CsCl$ unit cell (edge length '$a$')?

How many nearest neighbours are there for $Si$ and $O$ atoms in quartz crystals?

In a mixed oxide of two metals $X$ and $Y$,divalent $X^{2+}$ ions occupy $50\%$ of the tetrahedral voids,while trivalent $Y^{3+}$ ions occupy $50\%$ of the octahedral voids. The formula of the oxide is:

$A$ solid compound contains atoms $X, Y,$ and $Z$. In its unit cell,atoms $X$ are at the corners,atoms $Y$ are at the body center,and atoms $Z$ are at the face centers. The formula of the compound is:

The number of unit cells present in $39 \ g$ of potassium if it crystallizes as a body-centered cubic $(BCC)$ structure is ($N = \text{Avogadro number}$,$\text{At. wt. of potassium} = 39$).