A solid has a bcc structure. If the distance of closest approach between the two atoms is $1.73\mathrm{ }\mathrm{Å}$ . The edge length of the cell is:

• Correct answer
  A

  $200\mathrm{ }\mathrm{p}\mathrm{m}$
• B

  $\sqrt{\frac{3}{2}}\mathrm{ }\mathrm{p}\mathrm{m}$
• C

  $142.2\mathrm{ }\mathrm{p}\mathrm{m}$
• D

  $\sqrt{2}\mathrm{ }\mathrm{p}\mathrm{m}$

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