Each rubidium halide crystallising in the NaCl type lattice has a unit cell length 0.30 Å greater than for corresponding potassium salt (r_(K^+)=1.33 Å) of the same halogens . Hence, ionic radius of Rb^+ 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 length 0.30 Å greater than for corresponding potassium salt (r_(K^+)=1.33 Å) of the same halogens . Hence, ionic radius of Rb^+ is
Answer» 1.03 Å 1.18 Å 1.48 Å 1.63 Å Solution :As RBX crystallies in NaCl type lattice, unit cell length of RbX =`2(r_(Rb^+)+r_(X^-))` Unit cell length of KX =`2(r_(K^+) + r_(X^-))` `therefore 2(r_(Rb^+)+r_(X^-))-2(r_(K^+)+r_(X^-))`=0.30 Å or `r_(Rb^+) - r_(K^+)`=0.15 Å or `r_(Rb^+) = r_(K^+)`+ 0.15 Å =1.33 +1.15=1.48 Å