Which of the following about Atoms is NOT correct?

The correct answer is Option (3) → Atoms are capable of an independent existence under ordinary conditions.

Atoms of most elements cannot exist on their own; they join with other atoms to form molecules or ions. The smallest particle that can exist independently under ordinary conditions and shows all the properties of the substance is the molecule. Only the atoms of noble gases, such as helium and neon, exist singly.

• Option (1) Atom is very small, smaller than anything that we can imagine. — True about atoms (Incorrect). An atom’s radius is of the order of \(10^{-10}\) m, far too small to be seen even under an ordinary microscope.

• Option (2) Atoms can not usually exist independently and retain all their chemical properties. — True about atoms (Incorrect). Most atoms exist only in combination; two oxygen atoms, for example, join to form an \(\ce{O2}\) molecule.

• Option (3) Atoms are capable of an independent existence under ordinary conditions. — Not true about atoms (Correct). Independent existence under ordinary conditions belongs to the molecule, not to the atom.

• Option (4) The entire world is made of atoms. — True about atoms (Incorrect). All matter, living or non-living, is made of atoms, the building blocks of matter.