The number of electrons in the outermost '$L$' shell of an atom is $5$.
$(a)$ Write its electronic configuration.
$(b)$ What is its valency and why?

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

Explain the following with one example of each:
$(i)$ Atomic number
$(ii)$ Mass number

Will $^{35}Cl$ and $^{37}Cl$ have different valencies? Justify your answer.

$(a) (i)$ Name the scientist who proposed this model of the atom.
$(ii)$ Write the three postulates of this model.
$(iii)$ How many maximum electrons can be accommodated in the $M$ orbit?
$(b)$ What are canal rays? Give the characteristics of canal rays.

$(a)$ Explain Bohr$-$Bury rules for the distribution of electrons into different shells.
$(b)$ Write the electronic configuration of an atom of sulphur. Also,draw a schematic diagram of its atom showing the distribution of electrons in its shells.