The "0.10 M" in the solution refers to the molarity or concentration of the solution. It means that there is 0.10 moles of H2SO4 in every liter of the solution.
The order of ions in a solution of H2SO4 can be determined by looking at the chemical formula of the compound. In this case, H2SO4 has 2 hydrogen (H) ions, 1 sulfur (S) ion, and 4 oxygen (O) ions. Therefore, the order of ions would be H+, S2-, and O2- in decreasing order.
The order of ions in a solution of H2SO4 is important because it affects the properties and behavior of the solution. For example, the concentration of each ion will determine the strength and acidity of the solution.
The phrase "decreasing order" in the question means that the ions are listed from highest to lowest concentration. In this case, the highest concentration ion will be listed first, followed by the next highest concentration, and so on.
The concentration of a solution directly affects the order of ions. In a higher concentration solution, there will be more ions present, and therefore the order of ions will be different compared to a lower concentration solution. The higher concentration solution will have a higher concentration of the first ion listed, followed by the next highest concentration ion, and so on.