Atoms of metals $\mathrm{x}, \mathrm{y}$ and $\mathrm{z}$ form face-centred cubic (fcc) unit cell of edge length ${\mathrm{L}}_{\mathrm{x}}$, body-centred cubic (bcc) unit cell of edge length ${\mathrm{L}}_{\mathrm{y}}$, and simple cubic unit cell of edge length ${\mathrm{L}}_{\mathrm{z}}$, respectively. If ${\mathrm{r}}_{\mathrm{z}}=\frac{\sqrt{3}}{2}{\mathrm{r}}_{\mathrm{y}};{\mathrm{r}}_{\mathrm{y}}=\frac{8}{\sqrt{3}}{\mathrm{r}}_{\mathrm{x}};{\mathrm{M}}_{\mathrm{z}}=\frac{3}{2}{\mathrm{M}}_{\mathrm{y}}$ and ${\mathrm{M}}_{\mathrm{z}}=3{\mathrm{M}}_{\mathrm{x}}$, then the correct statement(s) is(are)

[Given: ${\mathrm{M}}_{\mathrm{x}},{\mathrm{M}}_{\mathrm{y}}$, and ${\mathrm{M}}_{\mathrm{z}}$ are molar masses of metals $\mathrm{x}, \mathrm{y}$, and $z$, respectively. ${\mathrm{r}}_{\mathrm{x}},{\mathrm{r}}_{\mathrm{y}}$, and ${\mathrm{r}}_{\mathrm{z}}$ are atomic radii of metals $\mathrm{x},\mathrm{y}$, and $\mathrm{z}$, respectively.]

Consider the bcc unit cells of the solids $1$ and $2$ with the position of atoms as shown below. The radius of atom $\mathrm{B}\mathrm{ }$ is twice that of atom $\mathrm{A}.$ The unit cell edge length is $50\mathrm{ }\mathrm{\%}$ more in solid $2$ than in $1$ . What is the approximate packing efficiency in solid $2$ ?

The vacant space in bcc lattice unit cell is:

The packing efficiency of the face centered cubic (FCC), body centered cubic (BCC) and simple/primitive cubic (PC) lattices follows the order