Question

Which of the following is not a example of a molecule A H2s B Mn C KOH D O3

Answer 1

The correct answer is D.
molecules refer to the smallest particle in a compound or an element, which possesses the chemical properties of that compound or element. They  are also made up of atoms which are held together by chemical bonds as result of exchange or sharing of electrons.
The Formula given in option D is an atom not a molecule because it is not sharing any bond with any other atom.

Answer 2

O3 is the correct answer :)!!