Aluminium crystallizes in face centered cubic structure, having atomic radius 125pm. The edge length of unit cell of aluminium is

1. 253.5 pm
2. 353.5 pm
3. 465 pm
4. 250 pm

Solution: 353.5 pm

$ For\text{ }a~FCC~or~~CCP~unit\text{ }cell,we\,have: $

$ 4r=\surd 2\times a $

$ \Rightarrow a=\frac{4r}{\surd 2}=353.5pm $