Which of the following metals reacts readily with cold water?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Calcium
Only the most reactive metals react with cold water. Calcium reacts with cold water to form calcium hydroxide and hydrogen gas; the bubbles of hydrogen stick to the metal and make it float.
Why the other options are incorrect
Option (1) Gold — Incorrect. Gold is among the least reactive metals and does not react with water at all.
Option (2) Silver — Incorrect. Silver is also very unreactive and does not react with water.
Option (3) Magnesium — Incorrect. Magnesium does not react with cold water; it reacts with hot water to form magnesium hydroxide and hydrogen.