Question

Consider the list of following substances. How many of the following are pure substances?
Oxygen, fluorine, paints, hydrochloric acid, methane
A.) 1
B.) 2
C.) 3
D.) 4

Answer 1

Hint: So, in this problem many elements, compounds or molecules are given. And you have to select the compounds which don’t have similar types of particles.

Step by step solution:
So, here we know that pure substances contain particles of similar types in it. Also we can say that pure substance is a material that has a constant composition and has consistent properties throughout the sample.
The substances which consist only of one type of atom, molecule, or compound are called as pure substances also called as homogeneous mixture.
Generally, elements and compounds are the pure substances.
So, oxygen gas only oxygen atoms, fluorine contains only fluorine atoms, methane contains only methane molecules, hydrochloric acid contains only one type of acid, but in paint there is a mixture of different types of particles. Paint is made of four main components which are resin, additives, solvent, and pigment.
So, from explanation we can say that oxygen, fluorine, hydrochloric acid and methane are pure substances, whereas paint is impure.
The correct answer is “D”.

Note: Don’t get confused with the hydrochloric acid and methane because methane is a single substance which has its own specific properties and it contains hydrogen and carbon in it. We can’t count hydrogen and carbon different-different. Similar concept is for hydrochloric acid.