Alkaline earth metals react with certain substances to produce hydrogen gas. Which of the following will result in hydrogen gas formation? Provide a balanced reaction.
a) Beryllium (Be) and O₂
b) Barium (Ba) and CO₂
c) Calcium (Ca) and H₂O
d) Strontium (Sr) and O₂

• A. Beryllium (Be) and O₂
  2 Be(s) + O₂(g) → 2 BeO(s)
• B. Barium (Ba) and CO₂
  Ba(s) + 2 CO₂(g) → BaO(s) + CO(g) + heat
• C. Calcium (Ca) and H₂O
  Ca(s) + 2 H₂O(l) → H₂(g) + Ca²⁺(aq) + 2 OH^–(aq) + heat
• D. Strontium (Sr) and O₂
  2 Sr(s) + O₂(g) → 2 SrO(s)

Answer: (C)

Verified step by step guidance

1. Identify the general reaction pattern for alkaline earth metals with water: Alkaline earth metals react with water to produce hydrogen gas and a metal hydroxide.
2. Examine the given reactions to determine which involves an alkaline earth metal reacting with water. The reaction of calcium (Ca) with water is: Ca(s) + 2 H2O(l) → H2(g) + Ca2+(aq) + 2 OH–(aq) + heat.
3. Verify that the reaction produces hydrogen gas (H2). In the reaction of calcium with water, hydrogen gas is indeed produced.
4. Write the balanced chemical equation for the reaction: Ca(s) + 2 H2O(l) → H2(g) + Ca2+(aq) + 2 OH–(aq) + heat. Ensure that the number of atoms for each element is equal on both sides of the equation.
5. Conclude that the reaction of calcium with water is the correct choice for producing hydrogen gas among the given options.