Radius of cation and anion are $2.5 \ \mathring{A}$ and $2.6 \ \mathring{A}$ respectively. If a cubic crystal system is prepared by combination of above cation and anion then edge length of unit cell is ................ $\mathring{A}$ (Take $\sqrt{3} = 1.7$)

Fill in the blanks:
$1.$ Density of unit cell $(d) = ........$
$2.$ Mass of atoms present in unit cell $(m) = ........$

The volume occupied by a single $CsCl$ ion pair in a crystal is $7.014 \times 10^{-23} \ cm^{3}$. The smallest $Cs^{+}-Cs^{+}$ inter-nuclear distance is equal to the length of the side of the cube corresponding to the volume of one $CsCl$ ion pair. The smallest $Cs^{+}-Cs^{+}$ inter-nuclear distance is nearly:

Copper crystallises in $fcc$ unit cell with cell edge length of $3.608 \times 10^{-8} \, cm$. The density of copper is $8.92 \, g \, cm^{-3}$. Calculate the atomic mass of copper. (In $u$)

The face diagonal of a cubic close-packed unit cell is $4 \ \mathring{A}$. What will be the edge length?

How can the crystal form of ice be examined?