Question

Which of the following materials fall in the category of a pure substance? (a) Ice (b) Milk (c) Iron (d) Hydrochloric acid (e) Calcium oxide (f) Mercury (g) Brick (h) Wood (i)Air

Answer 1

Pure substances:

• “Pure substances can be elements or compounds.”
• A substance can not be separated by any physical method.
• The properties/composition of a pure substance is fixed.
• Examples of substances are sugar as well as iron.

Properties of substance:

• A pure substance is composed of only one state of matter.
• It has a definite mass/weight/volume.
• It is composed of atoms/molecules.

Out of the given options, the materials that fall under the category of pure substances are Ice, iron, hydrochloric acid, calcium oxide as well as mercury. While Milk is a colloidal solution. Brick and Air are considered mixtures as they are made up of more than one substance.