Question

What gases does a Jovian planet not have?

Answer 1

Jovian planets will have all of the elements which are gases at its temperature and pressure.

Explanation:

Let's take Jupiter as an example. Its temperature is about 165K. The only elements which are gases at that temperature are: Hydrogen, Helium, Nitrogen, Oxygen, Fluorine, Neon, Argon and Krypton.

Other elements which are gases on Earth like Chlorine are liquid at the temperature of Jupiter. Fluorine and Oxygen are also very reactive and will typically be in the form of compounds which are not gases at those temperatures. Fluorine only occurs as a gas on Earth artificially.

Gas giants like Jupiter are about 90% Hydrogen and about 10% Helium. All of the other gases are present but in very small quantities.

The ratio of elements depends on the element ratio of the nebula from which the solar system formed. If it dated from the big bang then the only gases present would be Hydrogen and Helium. Many solar systems such as our own, were formed from planetary nebulae which are the remnants of a dead star. These will contain small quantities of heavier gaseous elements.

So, the only gas which is common on Earth and unlikely to be a gas on Jupiter is Oxygen which will probably only exist there in the form of water and other oxides.