Question

A certain element crystallises in a bcc lattice of unit cell edge, length 27ºÅ. If the same element under the same conditions crystallises in the fcc lattice, the edge length of the unit cell in Å will be………. (Assume each lattice point has a single atom)

[Assume $\sqrt{3}=1.73,\sqrt{2}=1.41$]

Answer 1

Answer: 33 

Explanation:: 

for bcc structure $4r=\sqrt{3}a$

                            $r=\frac{\sqrt{3}a}{4}$   …1

For FCC structure $4r=\sqrt{2}a$ 

                               $r=\frac{\sqrt{2}a}{4}$ …2

From 1 and 2