Consider the following elements: calcium, rubidium, strontium, and lithium. Which will react most violently with water? Write the balanced reaction equation that occurs.

• A. Calcium; Ca(s) + 2 H₂O(l) → Ca²⁺(aq) + 2 OH^–(aq) + H₂(g)
• B. Rubidium; 2 Rb(s) + 2 H₂O(l) → 2 Rb⁺(aq) + 2 OH^–(aq) + H₂(g)
• C. Strontium; Ca(s) + 2 H₂O(l) → Sr²⁺(aq) + 2 OH^–(aq) + H₂(g)
• D. Lithium; 2 Li(s) + 2 H₂O(l) → 2 Li⁺(aq) + 2 OH^–(aq) + H₂(g)

Answer: (B)