Question

Which of the following is not a compound?
(A) Sulphur dioxide
(B) Chalk
(C) Lead
(D) Sulphuric acid

Answer 1

Compounds generally have two or more elements present in the uniform composition in the compound state. Thus, a compound is a molecule made up by a combination of more than one element.

Complete step by step answer:
A compound is a chemical substance that is composed of many identical molecules that are composed of atoms from more than one element held together by chemical bonds.
If a molecule consists of atoms of only one element is not considered as a compound.
Depending on how the , atoms are held together, we have four types of component:
(a) Molecules made by covalent bonds.
(b) Ionic compounds made by ionic bonds.
(c) Intermetallic compounds by metallic bonds.
(d) Complexes held by coordinate covalent bonds.
In the given option in question:
Option (A): Sulphur dioxide ($S{O_2}$ ) is a compound.
Option (B): Chalk is some carbonate $CaC{O_3}$ and it is a chemical compound.
Option (C): Lead ($Pb$) is not a compound, it is an element. Elements are simple substances that cannot be broken down by reactions.
Option (D): Sulphuric acid is also a compound having chemical formula ${H_2}S{O_4}$ .
Hence, Lead is not a compound

So, the correct answer is Option C.

Note: Compounds are made using a variety of bonding and forces. Such as London dispersion forces, covalent bonds, and ionic bonds, hydrogen bonds.
Compound can be converted to a different compound by interaction with a second chemical compound such as:
$AB + CD \to AD + CB$
Where A,B,C,D are atoms and AB,CD,AD,CB represents the unique compounds.
So the basic difference to differentiate between an element and compound is that an element consists of a single type of atom whereas a compound consists of two or more types of elements held together by bonds.