(a) Define 'Mass defect' and 'Binding energy' of a nucleus. Describe 'Fission process' on the basis of binding energy per nucleon. (b) A deuteron contains a proton and a neutron and has a mass of $2.013553 \text{ u}$. Calculate the mass defect for it in $\text{u}$ and its energy equivalence in $\text{MeV}$. ($m_p = 1.007277 \text{ u}$, $m_n = 1.008665 \text{ u}$, $1 \text{u} = 931.5 \text{ MeV/c}^2$)