Which statement best describes the general products of a reaction between any Group 1 metal and water?

• A. A metal oxide and oxygen gas
• B. A metal hydroxide and hydrogen gas
• C. A metal chloride and oxygen gas
• D. A metal carbonate and hydrogen gas

Answer: (B)

When a Group 1 metal reacts with water, the metal donates its outer electron to form a +1 ion, and the water provides the hydroxide part. The typical outcome is a metal hydroxide and hydrogen gas. The general equation shows two metal atoms reacting with two water molecules to give two metal hydroxide molecules and one molecule of hydrogen: 2 M + 2 H2O → 2 MOH + H2. In plain terms, the metal forms MOH, which is an alkali metal hydroxide that dissolves to make the solution strongly basic, and hydrogen gas is released.

This happens because the water supplies the OH− group and H atoms; the metal is oxidized from 0 to +1, and the hydrogen in water is reduced to H2, which escapes as gas. The other choices would require different reagents or products (like oxygen gas, chloride from a chloride source, or carbonate from CO2), so they don’t describe what occurs with a Group 1 metal reacting with water.