If the cation is present in the tetrahedral void,what is the radius ratio ${r_ + }/{r_ - }$?

What are two types of crystal structures shown by ice at different pressures?

In a $BCC$ lattice containing $X$ and $Y$ type of atoms, $X$ type of atoms are present at the corners and $Y$ type of atoms are present at the body center. In its unit cell, if three atoms are missing from the corners, the formula of the compound is:

In a face-centred cubic $(FCC)$ unit cell,what fraction of the edge length is not covered by the constituent atoms?

$A$ binary compound $(A^{+} B^{-})$ has a zinc blende structure where $B^{-}$ ions form the lattice and $A^{+}$ ions occupy $25\%$ of the tetrahedral voids. What is the formula of the compound?

If the length of the body diagonal of a $FCC$ unit cell is $x \ \mathring{A}$, the distance between two nearest octahedral voids in the cell in $\mathring{A}$ is