The bromine atom possesses $35$ electrons. It contains $6$ electrons in $2\mathrm{p}$ orbital, $6$ electrons in $3\mathrm{p}$ orbital and $5$ electrons in $4\mathrm{p}$ orbital. Which of these electron experiences the lowest effective nuclear charge ?

Find (a) the total number and (b) the total mass of neutrons in $7 \mathrm{mg} \mathrm{of}$ ${}^{14}\mathrm{C}$. 

(Assume that mass of a neutron= $1.675\times {10}^{-27} \mathrm{kg}$)

How many neutrons and protons are there in the following nuclei ?

${}_6{}^{13}\mathrm{C}, {}_8{}^{16}\mathrm{O}, {}_{12}{}^{24}\mathrm{Mg}, {}_{26}{}^{56}\mathrm{Fe}, {}_{38}{}^{88}\mathrm{Sr}$

Write the complete symbol for the atom with the given atomic number (Z) and atomic mass (A)