[填空题]
Common salt, NaCl, h-5w0 nj4taxdmas a densietw7b pd+--j xty of $ 2.165\ \text{g/cm}^3 $. The molecular weight of NaCl is 58.44. Estimate the distance between nearest neighbor Na and Cl ions. [Hint: Each ion can be considered to have one "cube" or "cell" of side $ s $ (our unknown) extending out from it.] $s$ = nm
