# Calculate the distance between $Na^+$ and $CI^−$ ions in NaCI crystal if its density is $2.165 gcm^{−3}$. [Molar mass of $NaCI = 58.5 gmol^{−1};N_A =6.02 × 10^{23} mol^{−1}$]

$2.82\times 10^{-8}cm$