If $\mathrm{M}$ is atomic mass of element and $\mathrm{a}$ is edge length of unit cell then the formula to calculate density is

• Correct answer
  A

  $\rho=\frac{n M}{a^3 N_A}$
• B

  $\rho=\frac{a^3 N_A}{n \times M}$
• C

  $\rho=\frac{a^3 M}{n N_A}$
• D

  $\rho=\frac{M N_A}{a^3 n}$

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