A, the minimum energy of the photon emitted by the hydrogen atom when it transits from a high energy level to a ground state is 10.2eV, which is ultraviolet light. Irradiating the zinc plate will definitely produce photoelectric effect, so A is wrong;

B. When the hydrogen atom transits from a high energy level to an energy level of n=3, the emitted photon energy is less than 1.5 1eV, which is infrared and has obvious thermal effect, so b is wrong;

C, the minimum energy of ultraviolet photons is 3. 1 1eV, and the ionization energy of hydrogen atom with n=2 level is 3.4eV, so ultraviolet rays cannot be absorbed by hydrogen atom with n=2 level, and C is wrong;

D, the minimum energy of ultraviolet photons is 3. 1 1eV, and the ionization energy of hydrogen atom with n=3 energy level is 1.5 1eV, so hydrogen atom with n=3 energy level can absorb ultraviolet rays at any frequency and ionize hydrogen atoms, so d is correct;

Therefore, choose: d.