Question

b) which changes are chemicals changes: dissolution, oxidation, melting, acidity, sublimation, density

Explanation:

Step1: Recall the definition of chemical change

A chemical change is a process that results in the formation of new substances.

Step2: Analyze each term

• Dissolution: Usually a physical change (e.g., salt dissolving in water, no new substance formed chemically in simple cases).
• Oxidation: A chemical reaction where a substance reacts with oxygen (or undergoes electron loss in a broader sense), forming new substances (e.g., iron rusting \(4Fe + 3O_{2}=2Fe_{2}O_{3}\)).
• Melting: A physical change (e.g., ice \(H_{2}O(s)\) melting to \(H_{2}O(l)\), same chemical formula).
• Acidity: A property, not a change.
• Sublimation: A physical change (e.g., dry - ice \(CO_{2}(s)\) subliming to \(CO_{2}(g)\), same chemical formula).
• Density: A physical property, not a change.

Answer:

Oxidation