Question

Match the properties that are possessed by the compounds given below.

• A. Efflorescence
• B. Deliquescence
• C. Hygroscopy

Answer 1

When the compound loses its water of crystallisation on exposure to dry air then it is known as efflorescence.
Examples of efflorescent substances :
Washing soda ($N{a}_{2}C{O}_3.10H_{2}O$), Glauber's salt ($N{a}_{2}S{O}_4.10H_{2}O$), etc.
Certain water soluble substances, when exposed to atmosphere at ordinary temperatures, absorb moisture to form solutions and it is known as deliquescence.
Examples of deliquescent substances :
Caustic soda $(NaOH$), Caustic potash ($KOH$), etc.
Certain substances absorb moisture from the atmosphere but do not form solution when they are exposed to the same. This is known as hygroscopy.
Examples of hygroscopic substances :
Conc. Sulphuric acid ($H_{2}S{O}_4$), quicklime ($CaO$), etc.