Which of the following statement(s) is/are correct for an ionic solid AB(s) having NaCl structure? [r_(+)//r_(-)=0.414,"edge length of cube = a"]

Which of the following statement(s) is/are correct for an ionic solid

1.	Which of the following statement(s) is/are correct for an ionic solid AB(s) having NaCl structure? [r_(+)//r_(-)=0.414,"edge length of cube = a"]
Answer» The number of neighbour of `A^(+)` which are at a distance 'a' from `A^(+)=6` The number of neighbour of `A^(+)` which are at a distance of `sqrt(3)/(2)` a from `B^(-)=8` The number of neighbour of `A^(+)` which are at a distance `((2-sqrt(2))/(sqrt(2)))r_(-)` from `A^(+)=6` The number of neighbour of `A^(+)` which are at a distance `((a)/(sqrt(2)))` from `A^(+)=12` Solution :(A) Neighbour of `A^(+)` which are at a distance 'a' are `A^(+)` and number is 6 (B) Consider CORNER `B^(-)` and central A+ (O.v. at cube centre), corner `B^(-)` is common in 8 unit cell, so `8A^(+)` are at a distance `(sqrt(3))/(2)` a from `B^(-)` (C ) GIVEN value, it is `r_(+)//r_(-)=0.414."So "A^(+)`is trapped between i.e. O.V. `6B^(-)`