Question

One of the constituents of baking powder is sodium hydrogen carbonate, the other constituent is:

Answer 1

Hint: Baking powder is used in cakes, muffins and cookies as a good leaving agent. Baking powder when added to the dough releases carbon dioxide due to the presence of baking soda. It is known that baking soda is slightly basic in nature with a pH of 8.3.

Complete answer:
-Sodium hydrogen carbonate (also sodium bicarbonate) commonly known as baking soda (especially in North America and New Zealand) or bicarbonate of soda is used widely in preparation of cakes, muffins, cookies. This is because baking soda on heating releases carbon dioxide that makes cake fluffy and soft.
-The salt is composed of a sodium cation ($\text{N}{{\text{a}}^{+}}$) and a bicarbonate anion ($\text{HC}{{\text{O}}_{3}}^{-}$). Sodium bicarbonate is a white solid that is crystalline in nature. However, it appears to be a fine powder like an amorphous solid.
 -It has a salty, alkaline taste resembling that of washing soda (sodium carbonate). This is because sodium bicarbonate is slightly basic.
Due to this baking soda when heated tastes bitter, which is unfavorable for food items. So, to neutralize the mild base we add a mild acid so as to preserve the taste of the food item. Hence the other constituent of baking powder is a mild edible acid, tartaric acid.

Therefore, the correct answer is option (D).

Note:
Acetic acid is one of the options given for the question above. It is a mild edible acid as well (dilute acetic acid is vinegar). However, the reaction between acetic acid and baking soda leads to formation of foam. This foam is because of the rapid release of carbon dioxide. This reaction is used to demonstrate chemical volcanoes as part of a project.