Question

Which of the following compounds are administered as antacids?
A) Sodium carbonate
B) Sodium hydrogen carbonate
C) Aluminium carbonate
D) Magnesium hydroxide

Answer 1

Antacids are the chemical compounds that have the property to neutralise the gastric acids. These substances have pH greater than 7, thereby depicting the basic nature of these substances.

Complete answer
We know that the chemical compounds which are able to neutralise the acids and form a salt as the final product are bases/ alkalis. Bases have pH more than $7.0$. The bases react with acids to form salts that are neutral in nature. So, from the definition of the antacids it is clear itself that antacids must be basic in nature as they are capable to neutralise the acid. Therefore, in other words we can define antacids as the chemical compounds which are basic in nature that react with gastric acids and neutralise them. Also, it is clear that antacids raise the gastric pH.
Sodium hydrogen carbonate is a chemical compound with chemical formula ${\rm{NaHC}}{{\rm{O}}_{\rm{3}}}$. It is also known as sodium bicarbonate and baking soda. Sodium bicarbonate is actually a very quick acting antacid. This is because sodium bicarbonate is alkaline in nature with a pH greater than $7.0$. It reacts with acids and releases ${\rm{C}}{{\rm{O}}_{\rm{2}}}$ gas. Due to this it helps in neutralising the gastric acid.
Also, magnesium hydroxide acts as an antacid due to its alkaline nature. Magnesium hydroxide is actually a chemical compound with chemical formula ${\rm{Mg}}{\left( {{\rm{OH}}} \right)_{\rm{2}}}$. The ${{\rm{H}}^ + }$ ions present in the gastric acids like HCl combine with the hydroxide ion i.e. ${\rm{O}}{{\rm{H}}^ - }$ ion present in the magnesium hydroxide to form a neutral salt. It is commonly used as milk of magnesia.

**Hence, options (B) Sodium hydrogen carbonate and (D) Sodium hydrogen carbonate, are the correct options.

Note: **
Thus, due to their alkaline nature both sodium hydrogen carbonate and magnesium hydroxide are used as antacid. They neutralise the gastric juices and relieves acidity by increasing the pH. Another reason what makes them suitable for use as an antacid is that they are safe to be taken by the body i.e. have lesser side effects.