Question

The following table gives the difference between elements and compounds. Which of the given difference is incorrect?

$\begin{array}{cc}\text{Elements}& \text{Compounds}\\ \text{(1) Pure substance}& \text{(1) Impure substance}\\ \text{(2) Has only one kind of atoms}& \text{(2) Has two or more kinds of}\\ & \text{atoms}\\ \text{(3) Represented by symbol}& \text{(3) Represented by chemical}\\ & \text{formula}\\ \text{(4) Smallest particle is atom}& \text{(4) Smallest particle is molecule}\end{array}$

• A. 2
• B. 3
• C. 4
• D. 1

Answer 1

The correct option is D

1

A compound is a pure substance made up two or more elements combined chemically in a fixed ratio by mass. Through chemical means, a compound can be broken down into simpler compounds or its elements or a combination of the two. Elements are also called pure substance because they are made up of the same kind of atoms throughout. The smallest particle of a compound is a molecule whereas that of an element is an atom.

A compound is represented by the chemical formula. For example, the chemical formula for ammonia is $N{H}_3$ and methane is $C{H}_4$. Elements are represented by atomic symbols. For example, the atomic symbol of copper, zinc, iron is Cu, Zn, Fe respectively.