Materials: Name the property of a substance that absorbs moisture from air upon exposure. Focus on the phenomenon where solids pick up atmospheric water; in some cases they even dissolve in it. Choose the correct term.

Given data

• Observation: A solid exposed to air absorbs moisture.
• Task: Name that property.

Concept/Approach
Two related terms exist: hygroscopic (general tendency to absorb moisture) and deliquescent (absorbs so much water that it forms a solution). Among the given options, the correct specific term is deliquescence.

Reasoning
• Deliquescence → moisture absorption leading to dissolution (e.g., CaCl₂, NaOH pellets). • Efflorescence is the opposite: losing water of crystallization. • Osmosis involves semipermeable membranes; desiccation is drying.

Final Answer
Deliquescence