Given below are two statements :
Statement I : The metallic radius of Na is 1.86 A° and the ionic radius of Na⁺ is lesser than 1.86 A°
Statement II : Ions are always smaller in size than the corresponding elements.
In the light of the above statements, choose the correct answer from the options given below :

Solution

Chemistry ma’am · 3 steps

Cations shrink and anions swell, so 'always smaller' fails the moment you look at Cl⁻.

1. Statement I. Na loses its single 3s electron to form Na⁺, so the whole third shell goes. The remaining 10 electrons feel the same 11 protons and are pulled in more tightly. So Na⁺ is about 95 pm, far below the metallic radius of 186 pm (1.86 Å). Statement I is correct.
2. Statement II. This works for cations but not for anions. When chlorine gains an electron, the nuclear charge stays the same while electron–electron repulsion rises, so the cloud spreads out.

   Pair	Atom radius	Ion radius	Ion is
   Na / Na⁺	186 pm	95 pm	smaller
   Cl / Cl⁻	99 pm	181 pm	larger

3. So. Statement I is correct and Statement II is false, because anions are bigger than their parent atoms. The answer is (d).

The idea to keep. Losing electrons makes an ion smaller than its atom. Gaining electrons makes it larger. Any statement that says ions are 'always' smaller or larger is false.

Answer from the NTA final answer key. Solution by PrepWiser.