If the distance between Na ⁺ and Cl ⁻ ions in sodium chloride crystal is x pm , the length of the edge of the unit cell is

Step-by-step solution

In fcc unit cell of NaCl , Na ⁺ ion is present at edge centre and Cl ⁻ ion is present at corner. Edge length, a=2 r⁺+2 r⁻ a=2 (r⁺+r⁻ )=2 x [ x=r⁺+r⁻ ]