(a) State the expression for the radius of the nth stationary orbit of an electron in a hydrogen-like ion.
(b) Using this expression, explain qualitatively why the radius of an allowed orbit
(i) increases rapidly as the principal quantum number n increases, and
(ii) decreases when the atomic number Z of the nucleus increases.
(c) Discuss any two physical consequences of the trends mentioned in part (b) for real hydrogen-like ions found in nature.