The atoms, in which the number of protons is same but the number of neutrons is different, are known as –

What is the mass number of an element, the atom of which contains two protons, two neutrons and two electrons?

The number of neutrons in the nucleus of plutonium nuclide ( ₉₄Pu²⁴²) is :

Number of electrons present in the species H₂⁺, He, H and O₂⁺ respectively are :

Which one of the following statements about the properties of neutrons is not correct?

What is the maximum number of electrons in the M-Shell ?