This General Science quiz on Acids, Bases and Salts puts 10 multiple-choice questions to you, the verified MCQs published with GK24's note on the topic, 3 of them asked in real previous-year papers. Every question carries a full explanation of why the correct option is right and why the other options are wrong, so you learn the fact behind the answer rather than the letter. Attempt it right after reading the note, keep to the timer, and use the explanations at the end to mark what needs another look. Sit it again before the exam as a quick revision of the topic.
10 questions with answers and explanations
Which of the following contains citric acid?
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
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 _______.
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 →What is the chemical formula of baking soda?
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.
Read the full explanation →The acid present in the sting of an ant is
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?
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 →Which acid is present in the gastric juice of the human stomach?
The stomach wall secretes hydrochloric acid, which makes the gastric juice strongly acidic, helps the enzyme pepsin digest proteins and kills many germs swallowed with food.
Read the full explanation →An aqueous solution of ammonium chloride, the salt of a strong acid and a weak base, will be
A salt takes its character from the strength of the acid and the base that formed it. Ammonium chloride comes from hydrochloric acid, a strong acid, and ammonium hydroxide, a weak base, so the strong partner dominates and the solution has a pH below seven.
Read the full explanation →Tooth decay begins when the pH of the mouth falls below about
Tooth enamel is made of calcium phosphate, the hardest substance in the body, and it begins to corrode when the pH in the mouth drops below about 5.5.
Read the full explanation →Bleaching powder is prepared by passing chlorine over
Bleaching powder, calcium oxychloride, is made in industry by passing chlorine gas over dry slaked lime, that is calcium hydroxide.
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