$(i)$ Write the postulates of the Bohr model of an atom.
$(ii)$ Draw a sketch of the Bohr model of an atom with atomic number $15$.

(N/A) $(i)$ The postulates of the Bohr model of an atom are as follows:
- Only certain special orbits,known as discrete orbits of electrons,are allowed inside the atom.
- While revolving in these discrete orbits,the electrons do not radiate energy.
$(ii)$ For an atom with atomic number $15$ (Phosphorus),the electronic configuration is $2, 8, 5$. The sketch shows the nucleus at the center,surrounded by three shells $(K, L, M)$: the $K$-shell contains $2$ electrons,the $L$-shell contains $8$ electrons,and the $M$-shell contains $5$ electrons.