can you tell me why electron ejected from inner shell in photoelectric effect?

Dear student,

For photoelectric emission to take place, the energy of incident radiation must be greater than the binding energy of the electron in a particular orbit. Since the inncermost electron in the lightest atom hydrogen even is 13.6eV, it is not possible for radiation(normally in range of 1.5eV to 3.1eV) to emit electrons from inner shells of higher elements.