GENERAL KNOWLEDGE

Detailed explanation-1: -W.C. Röntgen reported the discovery of X-rays in December 1895 after seven weeks of assiduous work during which he had studied the properties of this new type of radiation able to go through screens of notable thickness. He named them X-rays to underline the fact that their nature was unknown.

Detailed explanation-2: -One roentgen of X-rays may deposit anywhere from 0.01 to 0.04 Gy (1.0 to 4.0 rad) in bone depending on the beam energy. As the science of radiation dosimetry developed, it was realised that the ionising effect, and hence tissue damage, was linked to the energy absorbed, not just radiation exposure.