Achange in pressure would have the greatest effect on the solubility of a

The pressure has almost no effect on the solubilities of solids and liquids. If a solid is insoluble in a liquid we cannot increase its solubility in that liquid by applying pressure. Similarly if two liquids are immiscible, we cannot dissolve them in each other by applying pressure. If two liquids are miscible, even if you don't apply any pressure they mix in every proportion. 
However, the solubilities of gases in liquids are directly proportional to the pressure applied to the gases. Remember the fizzy drinks in which CO2 gas is dissolved under very high pressure. As far as the bottle is opened, pressure decreases and most of the dissolved gas try to escape from the liquid. 

Answer) by studying proton collisions hope this : )

Decomposition is the cycle at which bacteria breaks down any organic material into the soil