Statement - I : Helium is present in radio active minerals like pitchblende, monazite and clevite
Statement - II : The main commercial source of helium is natural gas

Statement I is true because helium is a common byproduct of the radioactive decay of certain minerals, including pitchblende, monazite, and clevite. These minerals contain radioactive elements such as uranium and thorium, which decay over time and release alpha particles (helium-4 nuclei) as a byproduct. The alpha particles then capture electrons from nearby atoms to form helium gas.

Statement II is also true because natural gas is currently the main commercial source of helium. Helium is extracted from natural gas deposits, which typically contain low concentrations of helium (around 0.3% by volume). The natural gas is processed in a facility called a cryogenic plant, where it is cooled to very low temperatures to separate out the helium from the other gases.