Give reason for the following observations. (a) Naphthalene balls disappear with time without leaving any solid. (b) We can get the smell of perfume sitting several meters away.

(a) Naphthalene balls disappearing without leaving any solid residue:
Naphthalene balls, commonly used as mothballs or insect repellents, sublimate. Sublimation is a process where a solid substance transitions directly into a gas without passing through the liquid phase. Naphthalene has this property; when exposed to air, it undergoes sublimation, converting from a solid directly to a gas. Hence, over time, the naphthalene balls gradually evaporate, disappearing without leaving any visible solid residue.

(b) The alluring scent of perfume can be detected from several meters away. This is because perfumes contain volatile aromatic compounds that have the ability to evaporate into the air. These tiny molecules quickly disperse into the surrounding atmosphere, making it easy for them to travel a significant distance. Whether it’s lingering on someone’s skin or clothing, the fragrance of the perfume can easily be perceived from afar due to the fast diffusion of these lightweight compounds.