Question

Identify the pure substance containing only one type of element.
A. Sugar
B. Diamond
C. Silica
D. Water

Answer 1

Hint: To solve this question, one should know the chemical composition of these Substances. If it is made up of different type of elements then it is not pure and if it is made up of only one type of element then it is a pure substance.

Complete Step by step answer:Sugar-
Sugar is a carbohydrate commonly known as table sugar and has a formula of sucrose. It is a disaccharide. It contains two monosaccharides that are fructose and glucose.
The chemical formula of sugar is $$C_{12}{H}_{22}{O}_{11}$$.Each molecule of sugar consists of 12 carbon atoms,11 oxygen atoms and 22 hydrogen atoms.
Hence, the substance is not made up of one single element.
Diamond:
Diamond is the only gem which is made up of a single element.it is typically 99.999% carbon the other 0.001 percent includes one or the other trace elements which are not the essential part of the chemistry. These trace elements are responsible for influencing its color and crystal structure.
Hence diamond is the pure substance made up of a single element only i.e. carbon.
Silica:
Silica is the other name given to the chemical compound silicon dioxide.
Silicon dioxide is a chemical compound with a molecular formula $$\left(Si{O}_2\right)$$ . it is most naturally found in nature as quartz. It has either white or colorless crystals.
Hence, the substance silica is made up of two elements silicon and oxygen.
Water:
Water is a simple molecule with a molecular formula of $$H_{2}O$$.
The chemical composition consists of two atoms of hydrogen and one atom of oxygen.
By the number of atoms, they combine in the ratio of $$2:1$$.
So, water is a substance which is made up of two elements hydrogen and oxygen.

Hence the correct option is D.

Note: Generally Students can get confused considering silica is made up of one substance or not as the term is very similar to the element silicon. But in actual it is the common name for silicon dioxide. Pure substances have the same composition throughout its whole volume.