Though a direct question it was fairly well attempted by most responding candidates.  Few candidates could hardly remember the conditions for the emission of photoelectrons or the particle characteristics of e-m waves.
             The expected answers are:
           (a)    Conditions for emission of photoelectrons
          
                 -     the wavelength of incident radiation must be less than the threshold wavelength of
                       metal surface
                                     
                  -     the frequency of incident radiation must be greater than the threshold frequency.

                  -     the energy of the incident photons (radiation) must be greater than the
                        Work function of the metal                                                      

                      (b)     Particle characteristics of electromagnetic waves

                   e.g -      Photoelectric effect
                         -     Thermionic emission
                         -      Radiations from heated bodies (Black body)
                         -      Emission and absorption of light  (incandescence).
                         -      Compton effect.