Elements and compounds can move from one phase to another phase when special what are present

Which factor is likely to impact the possible number of compounds ?

Hydrogenation reactions, in which h2 and an "unsaturated" organic compound combine, are used in the food, fuel, and polymer industries. in the simplest case, ethene (c2h4) and h2 form ethane (c2h6). if 140 kj is given off per mole of c2h4 reacting, how much heat (in mj) is released when 12 kg of c2h6 forms?

Athe top of a hill, an athlete on a skateboard has x joules of mechanical energy. how much mechanical energy will she have at the bottom of the hill? ignore the effects of friction.