21.The energy required to remove an electron from the first orbit of hydrogen atom to outside the atom is

22.In the spectral series of hydrogen atom, all the lines having their wavelengths in the visible region, are called

23.The equation for the radius of the orbit of quantum number n is given by

24.According to Rutherford atom model, the electrons are revolving around the nucleus so that centripetal force is provided by

25.The energy required to remove an electron from the orbit of hydrogen atom is called