Percentage of void space in AB solid having rock salt structure if `(r_(+))/(r_(-)) = (1)/(2)` having cation anion contact. Given `pi = 3.15`

Answer

0.3

Explanation

`r_(+) + r_(-) = (a)/(2) rArr (3r)/(2) = (a)/(2) , r - =(a)/(3) and r_(+) = (a)/(6)`
Packing fraction `= (4 XX (4)/(3) PI (r_(+)^(3) + r_(-)^(3)))/(a^(3)) = (4 xx (4)/(3) pi [((a)/(6))^(3) + ((a)/(3))^(3)])/(a^(3)) = 0.7`
Percentage void = 30%