Q. Which of the following element/s has diatomic atomicity?
1.Oxygen
2.Sulphur
3.Helium
Choose the correct answer from below given codes:

[A] 1 only

[B] 1 and 2 only

[C] 2 and 3 only

[D] 1, 2 and 3

Answer: A
Notes:

Explanation: The molecules of an element are constituted by the same type of atoms. Molecules of many elements, such as argon (Ar), helium (He) etc. are made up of only one atom of that element.

  • But this is not the case with most of the non metals. For example, a molecule of oxygen consists of two atoms of oxygen and hence it is known as a diatomic molecule, O2.
  • If 3 atoms of oxygen unite into a molecule, instead of the usual 2, we get ozone, O3. The number of atoms constituting a molecule is known as its atomicity.

Source: Science NCERT