Do these statements describe chemical or physical properties? (a) Oxygen gas supports combustion. (b) Fertilizers help to increase agricultural production. (c) Water boils below \(100^{\circ} \mathrm{C}\) on top of a mountain. (d) Lead is denser than aluminum. (e) Uranium is a radioactive element.

(a) Oxygen gas supports combustion: This statement is about a characteristic of oxygen gas that pertains to its chemical behaviour. Whenever a substance supports combustion, it implies that it can react with other substances (specifically, fuels) to trigger a chemical reaction, namely combustion. Hence, this statement describes a chemical property. (b) Fertilizers help to increase agricultural production: This statement is more a description of an application rather than a property, and it leans towards the chemical side as the effectiveness of fertilizers depends on the incorporation of nutrients into the plant, which is a chemical process.(c) Water boils below \(100^{\circ} \mathrm{C}\) on top of a mountain: This statement is about a characteristic of water under certain conditions. Boiling point is a physical property as it can be determined without changing the chemical nature of a substance. Hence, this statement describes a physical property.(d) Lead is denser than aluminum: Density is a property that can be calculated or measured without causing a substance to undergo a chemical change. Thus, this statement describes a physical property.(e) Uranium is a radioactive element: Radioactivity is a property that refers to the rate at which a substance disintegrates to produce radiation. It is associated with changes in the atomic nucleus, which is a part of the atom where the substance's identity is determined. So, this characteristic is related to a chemical property.