23. Baking soda solution will be of most help.
24. Milk should be given.
25. Distilled water is the choice.
Step-by-step explanation:
23. When someone is having acidity, it means the amount of hydrochloric acid in stomach has increased and this can lead to several problems and discomfort like heart burn and even esophageal reflux. This should be treated with basic solutions which will neutralize the acid. So baking soda is the most appropriate choice which will neutralize the hydrochloric acid forming carbon dioxide, sodium chloride and water.
24. As the child swallows acid, the problems he could face is burning of mucous membrane, severe pain and even stomach can be pierced by burning. These effects need separate treatment, but as a first aid, the child should be given milk as a choice as the acid should be diluted and the contact of acid with mucous membrane should be reduced.
25. Distilled water do have a pH nearest to 7 Because in the rain water, there's often mixture of different acids like sulphuric acid and nitric acid which comes from atmosphere and makes rain water acidic. Carbonated water is acidic due to carbonic acid. Well water and lake water are often basic due to aluminum and magnesium salts. But distilled water doesn't have any impurities.