Acid A, assuming the two acids have the same pH. The M stands for molarity which is how concentrated a substance is (basically the higher the molarity the more concentrated the acid is). However, pH refers to how acidic a substance is. If the two acids have different levels of acidity, the answer may be different.
The element which is least likely to undergo a chemical reaction is (4) neon.
The reason for this is because neon is a noble gas, which means that it doesn't react with other elements as well.
It is easiest to tell if a solution is saturated if there is residue on the bottom. If it crystallized, the solution is saturated. If it is a supersaturated solution, there will not be crystallization unless more of the solute is added, at which point all of it will crystallize.
