Question

which of which of the following materials fall we 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

Answer:

A pure substance does not have any other substance or impurity present and cannot be separated into other kinds of matter by physical processes. It has a definite set of properties such as boiling point, melting point, density, etc. Based on their chemical composition, pure substances are classified into two categories:

Elements.

A pure substance with only one kind of atom and cannot be broken into two or simpler substances by physical or chemical means is an element.

Compounds

A pure substance composed of two or more elements and chemically combined in a fixed proportion is called a compound.

Out of the given nine compounds, the following are pure substances.

Ice, iron, hydrochloric acid, calcium oxide, mercury are pure substances as they have definite composition.

Milk is a colloid and acts as a heterogeneous mixture; hence is not a pure substance.

Brick and air are made up of more than one substance; hence they also don’t fall into pure substances.