If you have two objects at the same temperature but different mass. Which object will have the most thermal energy?

If two objects made of the same substance have different masses or temperatures, you can determine which has more thermal energy. If the objects have different masses but are otherwise the same, the one with more mass has more thermal energy.

hydrogen is a compound or a single element and a element is a pure substence that cannot be separated into simpler subtances

clorine is a compound its a chemical substance that forms when two or more different elements combine

so both hydrogen and clorine are compounds