Question

The smallest particle of a compound showing all its properties is called its

• A. Atom
• B. Molecule
• C. Element
• D. Ion

Answer 1

The correct option is B

Molecule

Compounds: A compound is a substance that contains two or more kinds of atoms.

The explanation for the correct answer

Option B

• A molecule is a group of two or more atoms held together by a chemical bond.
• In a compound, the molecule is the smallest part that has an independent existence and retains all the properties of that compound.
• Molecules of compounds have atoms of different elements.
• Example: A molecule of water(${\mathrm{H}}_2\mathrm{O}$) consists of 2 $\mathrm{Hydrogen}$ atoms and 1 $\mathrm{Oxygen}$ atom.

The explanation for the incorrect answers

Option A

• Atoms are the building blocks of matter.
• It is the smallest unit of an element that exhibit all the properties of that element.
• Atoms are made up of 3 subatomic particles namely electrons, protons, and neutrons.
• Protons and neutrons are present inside the nucleus while electrons are present outside the nucleus.

Option C

• An element is a pure substance that cannot be broken down into any other substance.
• Every element is made up of its own type of atom.
• Atoms of the same element are identical in nature.

Option D

• Sometimes atoms become charged by gaining or accepting electrons. These charged species are known as ions.
• By losing electrons atoms form positively charged species called a cation.
• By gaining electrons atoms form negatively charged species called an anion.
• Example: Compound $\mathrm{Sodium}\mathrm{chloride}\left(\mathrm{NaCl}\right)$is formed by the combination of positively charged ${\mathrm{Na}}^{+}$cation and negatively charged ${\mathrm{Cl}}^{-}$anion.

Thus, option B, i.e., Molecule is the correct option.