The compound forming $ccp$ structure contains $9.6 \times 10^{23}$ atoms. Find the number of tetrahedral voids formed in it.

In a mixed oxide of $A$ and $B$,$A$ occupies all the octahedral voids while $B$ occupies $(2/3)$rd of the tetrahedral voids. The molecular formula of this oxide is

$A$ two-dimensional solid is made by alternating circles with radius $a$ and $b$ such that the sides of the circles touch. The packing fraction is defined as the ratio of the area under the circles to the area under the rectangle with sides of length $x$ and $y$. The ratio $r=b/a$ for which the packing fraction is minimised is closest to $.....$

In antifluorite structure,the negative ions

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

If $AB$ crystallizes in a zinc blende structure with $B^{-}$ ions at lattice points,what fraction of tetrahedral voids is occupied by $A^{+}$ ions? ............... $\%$