I have a doubt regarding the general outermost electronic configuration of f block elements. Why is it (n-2)f^(1-14)(n-1)d^(0-1)ns^2. The only exception i thought to this formula was thorium 5f^(0) 6d^(2) 7s^(2).So i feel it should be (n-2)f^(1-14)(n-1)d^(0-2)ns^2please help me as fast as possible.thanks...

The general electronic configuration of the f-block elements is given as :-
(n-2) f1-14, (n-1) s2 (n-1) p6 (n-1 ) d10, ns2.
The General electronic configuration of Lanthanides is [Xe] 4f1–14 5d1 6s2
:-The general electronic configuration of Actinides is [Rn] 5f1-14 6d0-1 7s2
see if you are telling that (n-2)f^(1-14)(n-1)d^(0-2)ns^2 be the electronic configuration then you are correct.But since this is an exception this is not included as one electron from 5f is shifted to 6d orbital.
Moreover in all the actinide series where the electron are added to 6d orbital is an exceptional electronic configuration.ex-Th,Pa,U,Cm ,Bk and Lw .
Because energy of 5f=6d,but 6 is outer as compared to 5f.Therefore filling should be 5f first then 6d.But these are exception.
For you just remember the exceptional configuration of Thorium

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