Why is the binding energy curve steep for light nuclei and falling off slowly for the heavy nuclei?

Assertion: Energy is released when heavy nuclei E undergo fission or light nuclei undergo fusion. Reason: For heavy nuclei, binding energy per nucleon increases with increasing Z while for light nuclei it decrease with increasing Z.

Why is the density of the nucleus more than that of the atom ? Show that the density of nuclear matter is same for all nuclei.

If a star can convert all the He nuclei completely into oxygen nuclei. Find the energy released per oxygen nuclei : [Mass of the nucleus He is 4.0026 amu and mass of oxygen nucleus 15.9994]

The binding energies of nuclei X and Y are E_1 and E_2 respectively. Two atoms of X fuse to give one atom of Y and an energy Q is released. Find Q

Obtain the binding energy of the nuclei ._(26)^(56)Fe and ._(83)^(209)Bi in units of MeV from the following data : m (._(26)^(56)Fe)= 55.934939 u, m (._(83)^(209)Bi)=208.980388 u