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 \( \sqrt3 = 1.73, \sqrt2 = 1.41\)]

Answer 1

Answer: 33 

Explanation:: 

for bcc structure \(4r=\sqrt3a\)

                            \(r={\sqrt3a\over4}\)   …1

For FCC structure \(4r=\sqrt2a\) 

                               \(r={\sqrt2a\over4}\) …2

From 1 and 2