Concept:An antacid is a mild base that neutralizes excess acid in the stomach.
Explanation:The stomach contains hydrochloric acid, which causes acidity when produced in excess.
A substance with pH above 7 is basic and can neutralize this acid.
Milk of Magnesia has a pH of
10.5, so it is alkaline.
Its hydroxide ions react with hydrogen ions in the stomach acid.
This reaction forms water and reduces the acidity.
Other options are acidic or neutral and would not relieve acidity.
Tomato juice has pH
4.1 and black coffee has pH
5.0, both are acidic.
Strong salt solution has pH
7.0, which is neutral and ineffective as an antacid.
Answer:C. Milk of Magnesia with pH
10.5