Final answer:
The statement that hydrogen is mostly found in stars and gas giants like Jupiter is true. Hydrogen is the most abundant element in the universe, central to stellar fusion, and predominates the composition of gaseous planets.
Step-by-step explanation:
The statement that hydrogen is found mostly in stars and gas giant planets such as Jupiter is true. Hydrogen is not only the lightest element in the periodic table but also the most abundant element in the universe. It serves a vital role as the fuel for the fusion reactions taking place in stars such as our Sun. These fusion reactions convert hydrogen atoms into helium, releasing vast amounts of energy in the process. Additionally, gaseous planets like Jupiter are predominantly composed of hydrogen. Even though detected exoplanets with masses greater than 100 MEarth suggest lower densities than a pure hydrogen planet, they are still largely composed of hydrogen and its compounds. This indicates that their inflated radii are, in part, due to additional factors such as the significant amount of radiated energy they intercept from their host stars, causing the planets to expand.