What characteristic differentiates gum from resin?

Gum is defined by its ability to dissolve in water, a characteristic that distinguishes it from resin. When exposed to water, gums are hygroscopic and can dissolve or swell, forming a gel-like consistency. This property makes gums useful in various applications, such as food production, pharmaceuticals, and cosmetics, where solubility is beneficial. On the other hand, resins do not dissolve in water in the same way and are typically hydrophobic, which contributes to their different uses, such as in varnishes or adhesives for their sealing and waterproofing properties.

The other characteristics mentioned are not primarily distinguishing features between gum and resin. For instance, while some gums may have a mild scent, resins are more likely to possess a stronger aroma, largely due to the volatile compounds they contain. The state of matter at room temperature varies, but typically, gums are often found in a semi-solid or liquid state depending on their specific formulation, rather than being solid in the same sense that many resins can be. Flammability is also not a unique characteristic that differentiates the two, as both can have varying degrees of flammability depending on their chemical composition.