Question

Match the following substances with their corresponding properties.

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

Answer 1

Hygroscopy is the phenomenon in which the substances absorb moisture from the surroundings, usually at room temperature. These substances do not change their state.
Examples: NaOH, honey, conc. $H_{2}S{O}_4$

Efflorescence refers to property of certain hydrated salts to lose water when left in open.
Examples: $N{a}_{2}C{O}_3.10H_{2}O$, $CaS{O}_4.2H_{2}O$, $CuS{O}_4.5H_{2}O$

Deliquescence, like hygroscopy, is also a tendency to absorb moisture from the air when exposed.
Here, the substance dissolves itself in moisture and form an aqueous solution.
Examples: $CaC{l}_2$, $FeC{l}_3$