Number of valence electrons in $Cl^-$ ion are :

Find the valency of chlorine,sulphur,and magnesium.

Sulphur dioxide $(SO_{2})$ is a colourless,pungent-smelling gas and is a major air pollutant.
$(a)$ Write the electronic configuration of its constituent elements,sulphur and oxygen.
(Given: $_{16}^{32}S, _{8}^{16}O)$
$(b)$ Write the valency of sulphur and oxygen.
$(c)$ Are sulphur and oxygen isotopes of the same element? Explain your answer.

In the atom of an element $X$,$6$ electrons are present in the outermost shell. If it acquires noble gas configuration by accepting the requisite number of electrons,what would be the charge on the ion so formed?

An atom with $3$ protons and $4$ neutrons will have a valency of:

State three rules suggested by Bohr and Bury for the distribution of electrons into different orbits (shells) of an atom.