Which of the following elements is NOT Diatomic?
(A) Chlorine
(B) Argon
(C) Sulphur
(D) Helium
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (B), (C) and (D) only
A diatomic element exists as molecules of two atoms joined together: hydrogen, nitrogen, oxygen and the halogens (fluorine, chlorine, bromine, iodine).
(A) Chlorine Diatomic (Incorrect). Chlorine gas is made of \(\mathrm{Cl_2}\) molecules, two atoms held by a single covalent bond, as in every halogen.
(B) Argon Not diatomic (Correct). Argon is a noble gas with a complete outer shell, so its atoms do not bond with one another; it exists as single atoms (monatomic).
(C) Sulphur Not diatomic (Correct). Solid sulphur is made of \(\mathrm{S_8}\) molecules, rings of eight atoms, so it is polyatomic.
(D) Helium Not diatomic (Correct). Helium is also a noble gas, with its only shell full (two electrons), so it exists as single atoms.