What is the chemical formula of baking soda?
- A.Na2CO3
- B.NaHCO3
- C.NaOH
- D.CaOCl2
Correct answer
Explanation
The correct answer is B, NaHCO3. Baking soda is sodium hydrogen carbonate, a mild, non corrosive base used as an antacid, as an ingredient of baking powder along with a mild edible acid such as tartaric acid, and in soda acid fire extinguishers, where it releases carbon dioxide. Option A is wrong because Na2CO3 is sodium carbonate, and its decahydrate is washing soda, used for cleaning and for softening hard water. Option C is wrong because NaOH is sodium hydroxide, caustic soda, a strong alkali obtained from the chlor alkali process. Option D is wrong because CaOCl2 is bleaching powder, made by passing chlorine over dry slaked lime. The pair that catches students out is sodium carbonate against sodium hydrogen carbonate, so remember that the one with hydrogen in the name is the baking soda used in the kitchen.
Read the full article: Acids, Bases and Salts: pH Scale and Common Salts
Practice Questions
View allWhich of the following contains citric acid?
- A.Tomato
- B.Orange
- C.Tamarind
- D.Sour milk
Show answer
Citrus fruits such as orange, lemon, lime and grapefruit owe their sharp sour taste to citric acid, which is the acid textbooks name for this family and the one examiners expect here.
Read the full explanation →The pH of a solution is 3. When its pH changes to 6, then the hydrogen ion concentration
- A.Increases 2 times
- B.Increases three times
- C.Decreases 100 times
- D.Decreases 1000 times
Show answer
The pH is the negative logarithm of the hydrogen ion concentration, so each rise of one unit means the concentration has fallen to one tenth.
Read the full explanation →When litmus is added to a solution of borax, it turns _______.
- A.Pink
- B.Orange
- C.Red
- D.Blue
Show answer
Borax, sodium tetraborate, is the salt of a strong base, sodium hydroxide, and a weak acid, boric acid, so its solution in water is basic.
Read the full explanation →The acid present in the sting of an ant is
- A.Formic acid
- B.Citric acid
- C.Lactic acid
- D.Tartaric acid
Show answer
The sting of an ant and the hairs of the nettle plant inject formic acid, also called methanoic acid, which is why the skin burns; rubbing on a mild base such as baking soda or the leaf of the dock plant relieves it by neutralising the acid.
Read the full explanation →Plaster of Paris is obtained by heating which of the following?
- A.Limestone
- B.Gypsum
- C.Quick lime
- D.Washing soda
Show answer
Plaster of Paris is calcium sulphate hemihydrate, made by heating gypsum, which is calcium sulphate dihydrate, to about 373 kelvin so that it loses three fourths of its water of crystallisation.
Read the full explanation →