Answer is: nucleus of Cd is 1.26 times greater. The Nuclear radius formula or radius of nucleus formula: R = R₀ · ∛A. R is nuclear radius. R₀ is empirical constant, R₀ = 1.2 10⁻¹⁵ m. A is number of nucleon. R(Fe) = 1.2·10⁻¹⁵ m · ∛56. R(Fe) = 4.59·10⁻¹⁵ m. R(Cd) = 1.2·10⁻¹⁵ m · ∛112. R(Cd) = 5.78·10⁻¹⁵ m. R(Cd) / R(Fe) = 5.78·10⁻¹⁵ m / 4.59·10⁻¹⁵ m. R(Cd) / R(Fe) = 1.26.
