and when this inner core exceeds the appropriate Chandrasekhar mass limits it becomes unstable and inaugurates the implosion of the inner core and consequently announces the death of the star in a catastrophic explosion. The relic is either a neutron star or black hole depending on the mass of the progenitors. If the stars are not too massive then they collapse and consequently bounce and explode in spectacular visual display commonly known as type-II or Ib/c supernovae. The collapse of the star is very sensitive to the entropy and to the number of leptons per baryon, $Y_{e}$ [@Nabi05; @Bethe79]. The neutrinos are considered as main sink of energy and lepton number until the core density reaches around $10^{10}g-cm^{-3}$. At later stage of the collapse this assumption is no longer legitimate as weak interaction rates increase with increase of stellar core density. For densities $> 10^{11}
g-cm{^-3}$, the neutrinos mean free paths become shorter and consequently they proceed through all phases of free streaming, diffusion, and trapping. The most tightly bound of all the nuclei in the inner core of star is $^{56}$Fe [@Cowan04] and further fusing of the nuclei is highly endothermic. The second bottleneck to the synthesis of heavier 