(i)    Both s and p orbital are grouped together fore calculating Z_eff whereas the radial probability distribution curves for a given n indicate a higher penetration or shielding effect of s as compared to p-orbital.
(ii)    All electrons irrespective of s, p, d or f orbital at position lower than the (n-1) shell shield the n shell electron with equal contribution of 1.00. This is unjustified because energetic different orbital cannot have the same contribution.
(iii)    Penetrating by higher occupied orbital (than the one considered) into inner orbital is well known but even then their contribution is ignored as per Slater rule 2a.

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