Which is mismatched for NaCl crystal?

• A

  $\frac{r^{+}}{r^{-}}=0.414$ to 0.732
• B

  Coordination number = 6:6
• Correct answer
  C

  Edge of unit cell $=\left(r^{+}+r^{-}\right)$
• D

  Crystal structure = fcc

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