In a face-centred cubic arrangement of $A$ and $B$ atoms,$A$ atoms are at the corners of the unit cell and $B$ atoms are at the face centres. If one of the $A$ atoms is missing from one corner of the unit cell,what is the simplest formula of the compound?

The $CORRECT$ statement$(s)$ for cubic close packed $(ccp)$ three dimensional structure is(are)
$(A)$ The number of the nearest neighbours of an atom present in the topmost layer is $12$
$(B)$ The efficiency of atom packing is $74 \%$
$(C)$ The number of octahedral and tetrahedral voids per atom are $1$ and $2$,respectively
$(D)$ The unit cell edge length is $2\sqrt{2}$ times the radius of the atom

What is the percentage efficiency of packing in $BCC$ structure (in $\%$)?

Which of the following elements has an $hcp$ structure?

In a solid,$B^{-}$ ions occupy corners of a cube forming $ccp$ structure. If $A^{+}$ ions occupy half the tetrahedral voids,the formula of the solid is:

Calculate the total number of tetrahedral and octahedral voids in $0.4 \ mol$ of a compound having such voids in it.