Question

betwee neutral atom and cation which has bigger size?why?

Answer 1

Neutral atom. Because if a Cation is formed e- are removed from it. The atom gains a p+ charge over it. Due to increased nuclear charge(p+) the electrons are pulled more closely towards the nucleus because like(-) attracts unlike(+). And hence a decrease on the size of the atom.

Answer 2

The neutral atom is bigger than a cation because the nuclear charge of the atom remains same although the total no. of electrons reduce thus the nuclear charge superpose over the cation reducing the size of the ion in respect to the atom ( of same element)