Solid State Question 87

Question: How many unit cells are present in a cube-shaped ideal crystal of $ NaCl $ of mass 1.00g-

[Atomic masses: Na = 23, Cl = 35.5]

Options:

A) $ 2.57\times 10^{21} $ unit cells

B) $ 5.14\times 10^{21} $ unit cells

C) $ 1.28\times 10^{21} $ unit cells

D) $ 1.71\times 10^{21} $ unit cells

Show Answer

Answer:

Correct Answer: A

Solution:

[a] $ \frac{1}{58.5}\times 6.023\times 10^{23}=1.029\times 10^{22} $ A unit cell contains $ 4N{{a}^{+}} $ ion and $ 4C{{l}^{-}} $ ions

$ \therefore $ Unit cell $ \text{=}\frac{1.029\times 10^{22}}{4}=2.57\times 10^{21} $ unit cell