3. which of the following is not considered part of the solar system?
a: terrestrial planets
b: jovian planets (my answer)
c: galazies
d: sun
4. the jovian planets contain a large percentage of the gases
a: nitrogen and argon
b: hydrogen and helium (my answer)
c: oxygen and nitrogen
d: hydrogen and oxygen

3. The option which is not considered part of the solar system are C. galaxies. The solar system revolves around the Sun, and includes all the planets in the Milky Way, both terrestrial ones (Mercury, Venus, Earth, and Mars) and Jovian ones (the remaining planets which are farther from the Sun). Sun is obviously in the center of the Solar system. As for 4. the Jovian planets contain a large percentage of the gases B. hydrogen and helium, you were correct here. This is because they are so much away from the Sun and their surfaces are not solid.