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Gold (atomic radius = 0.144 nm) crystallises in a face-centred unit cell. What is the length of a side of the cell?

$\begin{array}{1 1}0.407nm\\0.507nm\\0.307nm\\0.207nm\end{array} $

1 Answer

Radius of gold atom $r=0.144$nm
In face centred unit cell,face diagonal =$4r=\sqrt 2a$
$a=\large\frac{4r}{\sqrt 2}$$=2\sqrt {2r}$
$\Rightarrow \large\frac{4\times 0.144}{1.414}$nm
$\Rightarrow 0.407$ nm
answered Jul 30, 2014 by sreemathi.v

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