The interatomic distance for a metal is $3\times {10}^{-10}\mathrm{m}$ . If the interatomic force constant is $3.6\times {10}^{-9}\mathrm{N}/\mathrm{\AA }$, then the Young's modulus in  $\mathrm{N}/{\mathrm{m}}^2$ will be 

• A

  $1.2\times {10}^{11}$

• B

  $4.2\times {10}^{11}$

• C

  $10.8\times {10}^{-19}$

• D

  $2.4\times {10}^{10}$