Question

Which of the following is not a pure substance?
(A) Aerated water
(B) Carbon dioxide
(C) Oxygen
(D) Zinc

Answer 1

Hint: The three fundamental states of matter are solid, liquid, and gases. Other classifications of matter are pure substances and mixtures. A pure substance is only one kind of matter either one element or one compound with the same thing with a fixed, definite set of properties.

Complete step by step solution:
Pure substances are substances that have a particular composition, which cannot get separated into other forms of matter.
So, the pure substance is defined as the substance contains only one type of particle which is free from any mixture. For example, gold, silver, and iron are some examples of pure substances.
Based on the pure substance chemical composition, pure substance are two types- elements and compounds
(1) Elements: A pure substance with a single kind of atom is called an element, which cannot get broken into two or simple substances by physical or chemical reactions. Elements can be metals, non-metal, and metalloids.
For example, given oxygen is non-metal and zinc is a metal, are elements. Hence, oxygen and zinc are pure substances.
(2) Compounds: The pure substance with two or more elements that get chemically combined in a predetermined proportion. For example, two hydrogen and oxygen elements form a water compound in a fixed proportion.
Mixtures: the substances which contain two or more forms of matter are called a mixture.
For example, a solution of salt and water, sugar and water, different gases, etc.
Based on the composition, mixtures are classified into two types- homogeneous mixture and heterogeneous mixture.
(a) Homogeneous mixture: those mixtures throughout a uniform composition are homogeneous mixtures. For example, Aerated water is a homogeneous mixture of carbon dioxide and water.
(b) Heterogeneous mixture: a mixture in which is not uniform throughout the mixture. For example, a mixture of oil and water, vegetable soup.
Hence, aerated water is a homogeneous mixture, while carbon dioxide is a compound, zinc, and oxygen are elements that are a type of pure substance.

Correct options are (B), (C), and (D).

Note: A part of a sample that has uniform composition and properties is called a phase. Pure substances and homogeneous mixture are in a single phase. In a heterogeneous mixture, there are two or more phases. Each layer that is separated in a heterogeneous mixture has represented a phase.