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

If the nucleus $${}_{13}^{27}Al$$ has a nuclear radius of about 3.6 fm, them $${}_{32}^{125}Te$$ would have its radius approximately as

A nucleus $${}_Z^AX$$ has mass represented by M(A, Z). If M_p and M_n denote the mass of proton and neutron respectively and B.E. the binding energy in MeV, then

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