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Question: Answered & Verified by Expert
The number of unit cells present in $39 \mathrm{~g}$ of potassium if it crystallizes as body centred cube is ( $N=$ Avogadro number, At. wt. of potassium $=39$ )
ChemistrySolid StateAP EAMCETAP EAMCET 2011
Options:
  • A $\frac{N}{4}$
  • B $\frac{N}{2}$
  • C $\frac{N}{3}$
  • D $N$
Solution:
1355 Upvotes Verified Answer
The correct answer is: $\frac{N}{2}$
Potassium has bcc system
Number of mole $=39 / 39=1$ mole
1 mole of atoms $=6.022 \times 10^{23}$ atoms $=N$
$\because$ In bcc system 2 atoms are present in 1 unit cell.
$\therefore N$ number of atoms are present in $\frac{N}{2}$ unit cells.

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