When a metal X is treated with cold water, it gives a basic salt Y with molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z and also write the reaction involved.

AcademicChemistryNCERTClass 10

The salt is NaOH and its molar mass can be calculated as follows:
Hence, it is clear that X is sodium,
Y is sodium hydroxide 
Hydrogen is a highly inflammable gas and hence it easily catches fire.
Hence, Z is hydrogen.
The reaction can be shown by the following equation:
2Na + 2H2O→2NaOH + H2 + Heat
Updated on 10-Oct-2022 13:27:26