Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Loss of electron from hydrogen atom results in nucleus of ~$$1.5 \times 10^{-3}$$ pm size.
Reason R: Proton H$$^+$$ always exists in combined form.
In the light of the above statements, choose the most appropriate answer from the options given below:

Assertion A: Loss of electron from hydrogen atom results in nucleus of ~$$1.5 \times 10^{-3}$$ pm size.

When hydrogen loses its only electron, we are left with just a proton (H⁺). The size of a proton is approximately $$1.5 \times 10^{-3}$$ pm (= 1.5 femtometers). This is correct.

Reason R: Proton H⁺ always exists in combined form.

A bare proton (H⁺) is extremely small and has very high charge density. In aqueous solution, it immediately combines with water to form hydronium ion (H₃O⁺) or other hydrated species. It never exists as a free proton in solution. This is correct.

However, R does not explain A. The small size of the proton (A) is due to the nuclear dimensions, not because of its tendency to combine with other species (R). These are two independent facts.

The correct answer is Both A and R are correct but R is NOT the correct explanation of A.