Classify the following as physical or chemical properties: (a) The composition of a sample of steel is 98% iron, 1.5% carbon and 0.5% other elements. (b) Zinc dissolves in hydrochloric acid with the evolution of hydrogen gas. (c) Metallic sodium is soft enough to be cut with a knife. Most metal oxides form alkalis on interacting with water.

• Solution:

Answers: Physical properties are a) and c). Chemical properties are b) and d)

Explanation

1. Composition of a sample of steel is 98% iron, 1.5% carbon and 0.5% other elements. It is a chemical property because no new compound is formed as steel is an alloy and alloy and is a homogeneous mixture of two or more metals or of metallic elements with non-metallic elements.
2. It is a chemical property because zinc reacts with HCL to give out zinc chloride and hydrogen
3. The cutting knife will not involve any chemical reaction and did not form a new compound hence it is a physical
4. It is chemical property as the new compound is formed by the interaction of metal oxides with