Question

Which of the following is the smallest unit of a substance capable of independent existence.

• A. Radical
• B. Atom
• C. Molecule
• D. Cation

Answer 1

The correct option is C

Molecule

Explanation for the correct option

Option (c)

• Molecule: A molecule can be defined as the smallest particle of an element or a compound that is capable of independent existence and shows all the properties of that substance.
• An example of a molecule is a Water molecule(${\mathrm{H}}_2\mathrm{O}$)
• It is the smallest unit that can exist independently.

Explanation for incorrect options:

Option(a)

• Radical: it is the type of molecule having an unpaired electron.
• An example of a radical is a ${\mathrm{OH}}^{.}$
• It is not the smallest unit. They do not exist independently.

Option(b)

• Atom: The atom is the smallest unit that helps in the building up of matter.
• An example of an atom is $\mathrm{Li}$ .
• It can not exist independently. It always exists as a molecule.

Option(d)

• Cation: It is the type of ion which has a positive charge over it.
• An example of a cation is ${\mathrm{Li}}^{+}$.
• They do not exist independently.

Therefore, the correct option is an option©.