Which of the following chemical properties of sodium metal is typically observed during a reaction with water?

• A. It forms a precipitate when added to water.
• B. It remains unchanged and does not react with water.
• C. It dissolves in water without producing any gas.
• D. It reacts vigorously, producing hydrogen gas and a strong alkaline solution.

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the nature of sodium metal (Na) as an alkali metal, which is highly reactive, especially with water.
2. Step 2: Recall the general reaction of alkali metals with water, where the metal reacts to form a metal hydroxide and hydrogen gas.
3. Step 3: Write the balanced chemical equation for sodium reacting with water: \$2\mathrm{Na} + 2\mathrm{H_2O} \rightarrow 2\mathrm{NaOH} + \mathrm{H_2}$.
4. Step 4: Analyze the products: sodium hydroxide (NaOH) is a strong base, making the solution alkaline, and hydrogen gas (H₂) is released, often observed as bubbling or fizzing.
5. Step 5: Conclude that sodium does not form a precipitate, does not remain unchanged, and does not simply dissolve without reaction; instead, it reacts vigorously producing hydrogen gas and a strong alkaline solution.