How many unit cells are present in a cube-shaped ideal crystal of $NaCl$ of mass $1 \ g$?

The density of $\beta-Fe$ is $7.6 \ g \ cm^{-3}$. It crystallizes in a cubic lattice with $a = 290 \ pm$. What is the value of $Z$? $(Fe = 56 \ g \ mol^{-1}; N_{A} = 6.022 \times 10^{23} \ mol^{-1})$

$A$ metal crystallizes with a $FCC$ lattice, the edge of whose unit cell is $x \text{ pm}$. The diameter of this metal atom would be $\text{pm}$.

Niobium crystallizes in a body-centered cubic $(BCC)$ structure. If the density is $8.55 \ g \ cm^{-3}$,calculate the atomic radius of niobium. (Atomic mass of niobium $M_w = 93 \ g \ mol^{-1}$)

Calculate the number of unit cells in $1 \text{ cm}^3$ of metal if it forms a simple cubic structure with a unit cell edge length of $500 \text{ pm}$.

The density of the unit cell of $Li$ is $0.539 \ g/cm^3$ and the edge length of the unit cell is $3.5 \ \mathring{A}$. How many $Li$ atoms are present in a unit cell of lithium? (Atomic mass of $Li = 6.94 \ g/mol$)