The distance between Na ^ + and Cl ^ - ions in solid NaCl of...

For $NaClZ = 4$ and $M = 58 . 5$ gram

$d = \dfrac{Z \times M}{{N}_{A} \times Volume}$

$43 . 1 = \dfrac{4 \times 58 . 5}{6 . 02 \times {10}^{23} \times {\left[a\right]}^{3}}$

${a}^{3} = \dfrac{4 \times 58 . 5}{6 . 02 \times 43 . 1} \times {10}^{- 23}$

$= 0 . 9 \times {10}^{- 23}$

$= 9 \times {10}^{- 24}$

$a = 2 . 08 \times {10}^{- 8}cm$

${d}_{{Na}^{+} + {Cl}^{-}} = \dfrac{a}{2} = \dfrac{2 . 08 \times {10}^{- 10}}{2}m ≃ 1 \times {10}^{- 10}m$