Which of the following does NOT change when a chemical reaction take place?

Correct option is A

The correct answer is (a) Mass.
· According to the law of conservation of mass, the mass remains constant during a chemical reaction.
· In a closed system, the total mass of reactants equals the total mass of products, as atoms are neither created nor destroyed in a chemical reaction.
· While the properties and arrangement of the atoms change, the mass remains unchanged. However, other factors, such as physical and chemical properties, can change due to the formation of new substances.
Additional Knowledge:
· Physical properties: These often change during a chemical reaction due to the formation of new compounds.
· Volume: Volume can change, especially in reactions involving gases, due to the difference in spatial arrangement.
· Chemical properties: Chemical properties change because new substances with different chemical behaviors are produced.