In a mass spectrometer used for measuring the masses of ions, the ions are initially accelerated by an electric potential $$V$$ and then made to describe semicircular paths of radius R using a magnetic field B. If V and B are kept constant, the ratio $$\left( {{{ch\arg e\,\,on\,\,\,the\,\,ion\,\,} \over {mass\,\,of\,\,the\,\,ion}}} \right)$$ will be proportional to

The total energy of electron in the ground state of hydrogen atom is $$-$$ 13.6 eV. The kinetic energy of an electron in the first excited state is

The radius of germanium (Ge) nuclide is measured to be twice the radius of $${}_4^9$$Be. The number of nucleons in Ge are

The binding energy of deuteron is 2.2 MeV and that of $${}_2^4$$He is 28 MeV. If two deuterons are fused to form one $${}_2^4$$He then the energy released is