A photon collides with a stationary hydrogen atom in ground state inelastically. Energy of the colliding photon is 10.2 eV. After a time interval of the order of micro second another photon collides with same hydrogen atom inelastically with an energy of 15 eV. What will be observed by the detector?

One photon of energy 10.2  eV and an electron of energy 1.4 eV

Due to 10.2 eV photon one photon of energy 10.2 eV , an electron gets excited from n= 1 to n= 2 and when its come back to ground state it emits a photon of energy 10.2eV will be detected.

Due to 15 eV photon ( It is greater than binding energy of photon which is equal to 13.6eV)the electron will come out of the atom with energy = (15 - 13.6) = 1.4 eV.