Question

(a) A metal ‘A’ reacts violently with cold water and the gas evolved catches fire. Another metal ‘B’ when dipped in water starts floating. The metal ‘C’ does not react either with cold or hot water, but reacts with steam. The metal ‘D’ does not react with water at all. Identify the metals ‘A’, ‘B’, ‘C’ and ‘D’.

Hint:

Metals like potassium and sodium are highly reactive with water, magnesium reacts with steam, while noble metals like gold do not react with water.

Answer 1

A: Potassium (K)
B: Sodium (Na)
C: Magnesium (Mg)
D: Gold (Au) or any noble metal like Platinum (Pt)
- Metal ‘A’ reacts violently with cold water and the gas catches fire: Potassium reacts vigorously with water producing hydrogen gas, which catches fire due to heat evolved.
- Metal ‘B’ floats on water: Sodium reacts with cold water and forms hydrogen gas. The hydrogen bubbles stick to the metal, making it float.
- Metal ‘C’ does not react with cold or hot water but reacts with steam: Magnesium does not react with cold or hot water but reacts with steam to form magnesium oxide and hydrogen gas.
- Metal ‘D’ does not react with water at all: Metals like gold or platinum are noble metals and do not react with water under normal conditions.