Final answer:
Sodium, an alkali metal, readily dissolves in water to form a basic or alkaline solution characterized by the production of sodium hydroxide and hydrogen gas.
Step-by-step explanation:
The element that dissolves readily in water to form an alkaline solution is sodium, which belongs to the group of elements known as alkali metals. All alkali metals, including sodium, react with water to produce their respective metal hydroxide and hydrogen gas, resulting in a basic or alkaline solution.
Sodium hydroxide (NaOH), for instance, is a highly alkaline substance that rapidly releases OH- ions in water, raising the pH. Other alkali metals, such as potassium (K), behave similarly as demonstrated by the reaction:
2K (s) + 2H₂O (l) → 2KOH (aq) + H₂ (g)
This reaction clearly indicates the formation of a soluble hydroxide and the release of hydrogen gas.