Solid State - Result Question 46

46. Sodium crystallises in a bcc cubic lattice with the cell edge, $a=4.29 $ $Å$. What is the radius of sodium atom?

$(1994,2 M)$

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Answer:

Correct Answer: 46. $(1.86 $ $Å)$

Solution:

  1. In bcc arrangement of atoms : $4 r=\sqrt{3} a$, atoms on body diagonal remain in contact

$ \Rightarrow \quad r=\frac{\sqrt{3} a}{4}=\frac{\sqrt{3} \times 4.29}{4}=1.86 $ $Å $