RbCl has NaCl type lattice and its unit cell length is 0.30∘A greater than that for KCl. If rk+=1.33∘A, the ionic radius of Rb+ is
1.48 ∘A
1.63 ∘A
1.03 ∘A
None of these
aRbCl−aKCl=2(rRb++rCl−)−2(r+K+rCl−)=0.30∘A⇒rRb+=rK++0.15∘A=1.33∘A+0.15 ∘A=1.48 ∘A
Each rubidium halide crystallising in the NaCl type lattice has a unit cell length 0.30 ∘A greater than the corresponding potassium salt (rK+=1.33 ∘A) of the same halogen. Hence, ionic radius of Rb+ is: