Question

When a chlorine atom becomes chloride ion,its size?

• A. Remains unaltered
• B. Increases
• C. Decreases
• D. None of these

Answer 1

The correct option is B Increases

Cl atomic number is 17(17 electrons, 17 protons), when it gains electron then becomes $C{l}^{-}$ having 18 electrons and 17 protons. Due to excessive of electron, electron-electron repulsion becomes dominant as compared to electron-proton attraction. Due to this repulsion $C{l}^{-}$ size becomes larger.

Hence option B is correct answer.