The number of valence electrons in $Cl^{-}$ ion are

Which of the following statements are true for an element?
$(i)$ Atomic number $=$ number of protons $+$ number of electrons
$(ii)$ Mass number $=$ number of protons $+$ number of neutrons
$(iii)$ Atomic mass $=$ number of protons $=$ number of neutrons
$(iv)$ Atomic number $=$ number of protons $=$ number of electrons

An ion $X^{2-}$ contains $10$ electrons and $8$ neutrons. What are the atomic number and mass number of element $X$?

Match the names of the scientists given in column $A$ with their contributions towards the understanding of the atomic structure as given in column $B$.

Column $A$	Column $B$
$(a)$ Ernest Rutherford	$(i)$ Indivisibility of atoms
$(b)$ $J$.$J$. Thomson	$(ii)$ Stationary orbits
$(c)$ Dalton	$(iii)$ Concept of nucleus
$(d)$ Neils Bohr	$(iv)$ Discovery of electrons
$(e)$ James Chadwick	$(v)$ Atomic number
$(f)$ $E$. Goldstein	$(vi)$ Neutron
$(g)$ Mosley	$(vii)$ Canal rays

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?

State two main postulates of Thomson's model of an atom.