I) The valence electronic configurations for the S-block elements are:

Here are the solutions to the questions:

d)

i) The valence electronic configurations for the S-block elements are:

• Group I elements: $ns^1$ (where $n$ is the principal quantum number)
• Group II elements: $ns^2$ (where $n$ is the principal quantum number)

ii) The reactions of the Group II elements with water vary down the group as follows:

• Trend: The reactivity of Group II elements with water increases down the group.
• Explanation: As you move down Group II, the atomic radius increases, and the outermost valence electrons are further from the nucleus. This leads to a weaker electrostatic attraction between the nucleus and the valence electrons, resulting in a lower ionization energy. Consequently, it becomes easier for the atoms to lose their two valence electrons and form positive ions, making them more reactive with water. For example, beryllium does not react with water, magnesium reacts slowly with cold water but readily with steam, and calcium reacts vigorously with cold water.

iii) Balanced chemical equations for the reactions of the following elements with cold water:

• Na(s): $$2\text{Na}(s) + 2\text{H}_2\text{O}(l) \to 2\text{NaOH}(aq) + \text{H}_2(g)$$
• Mg(s): $$\text{Mg}(s) + 2\text{H}_2\text{O}(l) \to \text{Mg(OH)}_2(s) + \text{H}_2(g)$$