a. True. Characteristic radiation produced as a result of the photoelectric effect, in material with a low atomic number, has low photon energy and is absorbed almost immediately by the material. 

b. True. Incident photon energy must be greater than the binding energy of the electron to eject it from its shell. 

c. False. An increase in photon energy results in recoil electrons with higher energy and penetration. 

d. True. Reducing the tube voltage causes a reduction in photon energy, having a two-fold effect: i. There is more sideways scatter and less forward scatter towards the film ii. The scatter rays are less penetrating. 

e. False. The energy of the incident photon, in the photoelectric effect, is taken up in removing the electron (binding energy) and the rest becomes the kinetic energy of that electron. Kinetic energy of photo electron = photon energy – binding energy (Ek or EL). Hence, a higher atomic number results in a higher binding energy and therefore a photo electron with a lower energy.