If the lattice parameter for a crystalline structure is $3.6 \%$, then the atomic radius in fcc crystal is

• Correct answer
  A

  $1.27 \&$
• B

  $1.81 Å$
• C

  $2.10 Å$
• D

  $2.92 \&$

Solution

$$ 2 R=\frac{a}{\sqrt{2}} $$ $$ \therefore R=\frac{a}{2 \sqrt{2}} $$

Hence, the correct answer is option: 'A'.