Question

Number of unit cells in 4g of X(atomic mass = 40 ). Which crystallises in bcc pattern is:

[$ N_A is Avogadro number]

• A. $0.1N_A$
• B. $2\times 0.1N_A$
• C. $\frac{0.1\times N_A}{2}$
• D. $2\times N_A$

Answer 1

Answer: (C)

$\frac{0.1\times N_A}{2}$

Given that,

Atomic mass $X=40$

Now,

No of atoms unit cell for bcc $z=2$

No of atoms in 4g

$=\frac{4g}{40g}\times N_A$

$=0.1\times N_{A}atoms$

Now, no of unit cells

$=\frac{0.1\times N_A}{2}unitcell$

Hence, this required solution.