Production of X-rays is the reverse phenomenon of photoelectric effect. justify

When fast moving electrons strike on high atomic weight substance, X-rays areproduced and when radiations of sufficient frequency incident on the metal surface, electrons are emitted I.e.photoelectric effect take place. It means fast moving electronsproduce X-ray and X-ray I.e.radiation produce photoelectrons. Hence X-ray is the reverse phenomena of photoelectric effect

How is X-Ray produced in a lab?

Well, an interesting question indeed.

The basic principle for the production of X-ray is by deccelerating very fast moving electrons, so here might arise a question what happens to the energy of electrons? The energy of electrons is transferred to X-rays(minimum) and Heat energy. 

How do we deccelerate the fast moving electrons?

Simply by resistance force, for a fast moving electron, the energy possessed by it must be high, so we deccelerate the electrons by a target material which is of...

X-rays can penetrate through the flesh of meat but not through the bones why?

The flesh of meat made up from lighter elements but the bones are made from heavier elements. So, that X-rays penetrate through the flesh meat but not through the bones. Further, the penetrating power of X-rays can be controlled by controlling the voltage between cathode and the target. For a medical purposes, X-rays are produced in such a way that the X-rays penetrate through the flesh but not through bones.