Question

Which of the following is not an element:
A.22-carat gold
B.Graphite
C.Diamond
D.Rhombic sulphur

Answer 1

To answer this question, you should recall the concept of different types of materials. The material can be classified into three types: elements, compounds and mixture. Elements are substances that are made from a single type of atom. An element cannot be broken down into any other substance.

Complete Step by step solution:
Elements are substances that are made from a single type of atom. An element cannot be broken down into any other substance. These act as basic building blocks and everything in the universe is made from these. Examples include carbon, sulfur, oxygen, iron, copper, aluminium. Elements are generally denoted by their symbols.
A mixture is formed through simply mixing of elements or compounds. No new chemical bonds are formed. Mixtures can be separated using physical techniques for example filtration, chromatography, evaporation, magnetisation, flotation and distillation.
Compounds are substances that are formed from atoms of different elements that are connected by chemical bonds. The compounds can be separated into its constituent elements by a chemical reaction. Common examples are water ${{\text{H}}_2}{\text{O}}$ sodium chloride, methane. Compounds are denoted by the chemical formula.
Graphite and diamonds both compose of pure carbon only while rhombic sulphur is an allotrope of pure sulphur. Out of all the options, only 22-carat gold is a mixture of gold and silver or zinc and is thus, not an element.

Hence, the correct answer to this question is option A.

Note: The rest three options in the question i.e. graphite, diamond and rhombic sulphur are called allotropes. The term allotrope can be defined as one or more physical forms of a chemical element that occurs in the same physical state. These are structural types of the same element and therefore can exhibit differences in physical and chemical properties. Carbon atom due to its capability of having variable oxidation states makes it one the most important elements to have multiple numbers of allotropic forms.