Question

The density of $Ca{F}_2$ (fluorite structure) is $3.18$ g cm${}^{-3}$. The length (in pm) of the side of the unit cell is :

• A. $253$
• B. $344$
• C. $546$
• D. $273$

Answer 1

The correct option is C $546$

As we know, density $=d=\frac{nM}{V{N}_A}$
$V=a^3=\frac{4\times 78}{(3.18\times 6.023\times {10}^{23})}$ $⟹a=546$ pm