21. (i) Which two solutions will give a white precipitate when treated with dilute Hydrochloric acid followed by Barium chloride solution? (Type in the selected letters separated by commas. Leave no spaces around the commas.)   22. (ii) Which two solutions will give a white precipitate when treated with dilute Nitric acid followed by Silver nitrate solution?   23. (iii) Which solution will give a white precipitate when either dilute Hydrochloric acid or dilute Sulphuric acid is added to it?   24. (iv) Which solution becomes a deep/inky blue colour when excess of Ammonium hydroxide is added to it?   25. (v) Which solution gives a white precipitate with excess Ammonium hydroxide solution?