The ground state energy of hydrogen atom is $$-$$ 13.6 eV. When its electron is in the first excited state, its excitation energy is

Two nuclei have their mass numbers in the ratio of 1 : 3. The ratio of their nuclear densities would be

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