Which method is used to determine the edge length of a unit cell?

What is the volume of $1$ mole of a crystalline solid having unit cell edge length $16 \times 10^{-8} \ cm$,if its unit cell contains $24$ molecules?

The density of $Li$ metal is $0.53 \ g/cm^3$ and the edge length of its unit cell is $3.5 \ \mathop A\limits^o$. Calculate the number of $Li$ atoms in the unit cell. $(N_A = 6.02 \times 10^{23} \ mol^{-1}, M = 6.94 \ g \ mol^{-1})$

In an ionic compound with a $bcc$ structure, the distance between the two nearest ions is $173 \, pm$. What is the edge length of the unit cell in $pm$?

An element has a body-centred cubic $(bcc)$ structure with a cell edge of $288 \, pm$. The density of the element is $7.2 \, g/cm^{3}$. How many atoms are present in $208 \, g$ of the element?

If the crystal structure of $KCl$ is the same as that of $NaCl$,and the radius ratios are $r_{Na^+}/r_{Cl^-} = 0.55$ and $r_{K^+}/r_{Cl^-} = 0.74$,calculate the ratio of the edge lengths of the unit cells of $KCl$ and $NaCl$.