K+ and NH4+ ions have many similarities in their test. — s Block Elements Chemistry Question

💡 Solution & Explanation

Step 1: Down the group of alkali metals (Group 1), the nuclear charge increases, but the number of electron shells also increases. Step 2: The addition of new electron shells causes the valence electrons to be located further from the nucleus, which leads to a decrease in first ionization energy, electronegativity, and the hydration energy of the univalent cations. Step 3: Conversely, the atomic and ionic radii systematically increase down the group. Therefore, atomic radius increases with increasing atomic number, matching option (d).