Question

which shell is farthest shell in nucleus

Answer 1

Chemists use term as an "n" value as theoritically it can't be termed with any figure.

But generally 'Q' shell is the farthest shell in nucleus.

Answer 2

Electrons don't really work like that, and even if they did, there's no theoretical limit on the number of "shells" (which aren't really shells). So electrons are the farthest shell in nucleus.