Question

why does nature of canal rays depend upon nature of gas inside discharge tube whereas nature of cathode rays do not depend upon nature of gas inside a discharge tube?

Answer 1

Cathode ray is the beam of negatively charged electron generated in cathode ray tube experiment.
Canal ray also known as anode rays are made up of positively charged material particles formed by removal of electron.
Since the nature of electron does not change with the source So, charge by mass ratio for cathode ray does not change with the gas in the experiment.
But charge by mass ratio is different for different gases in case of canal rays. As the atomic masses of different gases are different and hence, the mass of anode ray particles varies in case of different gas. And it can be said that Nature of canal ray is highly dependent upon the nature of gas used in discharge tube.