Pls Help me understand how this integral is solved?

Chemistry questions. I cant understand. Urgent Help pls?

• Chemistry questions. I cant understand. Help? 1) A solution containing 0.10 mol dm^-3 ethanoic acid is expected to have a pH of value of 2.5. Why? 2) Magnesium hydroxide dissolves readily in ammonium chloride solution but not in sodium chloride solution because ammonium ion acts as an acid。 Why？ 3）The solubility product of Mg(OH)2 at 298K is 1.8X10^-11 mol^3dm^-9. Sodium hydroxide solution is added to 0.01 mol dm^-3 of magnesium chloride solution. What is the pH at which precipitate of Mg(OH)2 occurs , answer is 9.6 ...Why? 4) when solid ammonium chloride is added to ammonia solution, the pH of the solution decrease, the degree of dissociation of ammonia decreases but why there is no precipitate? 5) MgCO3 have solubility product in the range of 1X10^-5 to 1X10^-8 mol^2dm^-6, but why MgCrO4 and MgSO4 cannot 6)On descending the group 2 element, reactivity of elements increase? If you can help any of this, you can reply the answer Thanks .I really need help

• Answer:

  1. Since ethanoic acid is a weak acie (vinegar), then you should expect the pH to be low but not too low. 2. The NH4+ ion behaves as an acid and reacts with the OH- ions of the base.