The ratio of close-packed atoms to tetrahedral holes in cubic close packing is

$A$ solid element (metal) crystallises in $ABABAB$ type packing in three dimensions. If the density of the element and its atomic radius are $5.0 \ g/cm^3$ and $100\sqrt{2} \ pm$ respectively, the atomic mass of the element is $(N_A = 6 \times 10^{23} \ mol^{-1})$

The vacant space in $bcc$ lattice unit cell is ............ $\%$

The total number of octahedral void$(s)$ per atom present in a cubic close packed structure is

How much part of an atom occupies each corner of a $bcc$ unit cell?

When sodium is heated above $1000 \ K$,its crystal structure changes from $bcc$ to $fcc$. Assuming the metallic radius of the atom remains unchanged,the ratio of the fraction of volume occupied by atoms in $bcc$ and $fcc$ structures will be .......