Question

Assertion (A) : Radius of H+ is 1.5 × 10^–3 pm.
Reason (R) : H+ cannot exist independently.

Answer 1

Assertion (A): The radius of \( \text{H}^+ \) is \( 1.5 \times 10^{-3} \, \text{pm} \).
This is true. The hydrogen ion, \( \text{H}^+ \), also called a proton, is a bare nucleus consisting of just a single proton, which has a very small radius, approximately \( 1.5 \times 10^{-3} \, \text{pm} \). 

Reason (R): \( \text{H}^+ \) cannot exist independently.
This is also correct. The hydrogen ion \( \text{H}^+ \) is just a proton, and a proton cannot exist freely in an environment under normal conditions, as it would immediately attract an electron and form a neutral hydrogen atom, thus no free \( \text{H}^+ \) ions can exist independently. 

Explanation:
While both the assertion and reason are correct, the reason does not explain the assertion. The assertion gives the radius of the \( \text{H}^+ \) ion, which is a proton's radius, but this has no direct connection to whether \( \text{H}^+ \) can exist independently. The ability of \( \text{H}^+ \) to exist independently is more related to the nature of protons and their tendency to combine with electrons. 

Final Answer:
Both assertion and reason are correct, but reason is not a correct explanation of assertion.