What are the percentages of empty space in a cubic close-packed $(CCP)$ structure and a body-centered cubic $(BCC)$ structure,respectively?

$A$ compound is formed by elements $A$ and $B$ which crystallizes in a $CCP$ structure. Atoms of $A$ are at the corners and atoms of $B$ are at the face centers. If two atoms of $A$ are missing from the unit cell,what is the molecular formula of the compound?

What is the minimum number of spheres required to develop a tetrahedral void?

Which of the following crystal lattice will have a void fraction of $0.476$?

$A$ binary solid has a zinc blende structure with $B$ ions constituting the lattice and $A$ ions occupying $25\%$ of the tetrahedral holes. The formula of the solid is:

$A$ solid has $CCP$ arrangement having atoms $A, B, C$. If $A$ atoms are present at face centres,$B$ at corners and $C$ atoms occupy $50\%$ tetrahedral voids,then the molecular formula of the solid will be: