Each rubidium halide crystallising in the NaCl type lattice has a unit cell length0.30 Ågreaterthan for corresponding potassium salt ( r_(K^(+))= 1.33 Å ) of the same halogen. Hence, ionic radius ofRb^(+) is

Each rubidium halide crystallising in the NaCl type lattice has a unit

1.	Each rubidium halide crystallising in the NaCl type lattice has a unit cell length0.30 Ågreaterthan for corresponding potassium salt ( r_(K^(+))= 1.33 Å ) of the same halogen. Hence, ionic radius ofRb^(+) is
Answer» 1.03 Å 1.18 Å 1.48 Å 1.63 Å Solution :As RBX crystalliesin NaCl type LATTICE, unit CELL length of RbX = `2 ( r_(Rb^(+)) + r_(X^(-))` Unit cell length of KX =`2 (r_(K^(+)) + r_(X^(-))` ` 2( r_(Rb^(+)) + r_(X^(-)))-2 (r_(K^(+)) + r_(X^(-))) = 0.30 Å` ` or r_(Rb^(+)) - r_(K^(+)) = 0.15 Å` ` orr_(Rb^(+) = r_(K^(+)) + 0.15 Å = 1.33 + 1.15 = 1.48 Å`