Concept:Hygroscopic substances have a natural ability to absorb and retain moisture from the air.
Explanation:Salt, which is commonly sodium chloride (
NaCl), tends to pick up water vapor from humid surroundings.
Sugar also shows hygroscopic behavior by attracting water molecules and becoming sticky when exposed to air.
Silica gel is a classic example of a hygroscopic material and is often used as a drying agent.
Aluminum is a metal that does not show such an affinity for water vapor.
Unlike the other listed substances, aluminum does not absorb moisture from the atmosphere.
Thus, among the given options, aluminum is the one that is not hygroscopic.
Answer:D. Aluminum