Acids & Bases — Set 5

Correct Answer: A. Malic acid

Malic acid is the primary acid responsible for the tart taste of apples. The name is derived from the Latin word 'malum', which means apple. It is also found in other fruits like cherries and apricots.

Correct Answer: B. Potassium hydroxide

Potassium hydroxide is a strong base that completely dissociates into ions in water. It is used in alkaline batteries and in the manufacture of soft soaps. Strong bases have a high pH value, usually above 12.

Correct Answer: D. Sulfuric acid

Sulfuric acid was historically called Oil of Vitriol by ancient alchemists. This name was given because it was prepared by distilling green vitriol (ferrous sulfate). It is a dense, oily, and colorless liquid.

Correct Answer: B. 1.5 - 3.5

Gastric juice is highly acidic with a pH ranging from 1.5 to 3.5. This high acidity is necessary for the activation of digestive enzymes like pepsin. It also helps in sanitizing the food by killing ingested microbes.

Correct Answer: B. Tannic acid

Tea contains tannic acid, which belongs to a group of compounds called tannins. It contributes to the bitter flavor and the dark color of the brewed tea. Tannins are also found in wine and certain tree barks.

Correct Answer: B. Proton donor

According to the Brønsted-Lowry theory, an acid is a substance that can donate a proton (H+). This definition is broader than the Arrhenius theory as it doesn't require water. Every Brønsted acid has a corresponding conjugate base.

Correct Answer: D. Nitric acid

Nitric acid is a key industrial chemical used to produce nitrogen-based fertilizers. It is also a fundamental component in making explosives like TNT and nitroglycerin. Its strong oxidizing properties make it highly reactive.

Correct Answer: D. 10

Milk of magnesia is a basic suspension with a pH value of approximately 10. It is alkaline enough to neutralize stomach acid but safe enough for consumption. This makes it an effective household remedy for heartburn.

Correct Answer: D. Carbonic acid

Carbonic acid is formed when carbon dioxide is dissolved in water under pressure. It gives soft drinks their sharp, acidic bite and carbonated texture. It is a weak and unstable acid that decomposes back into CO2 and water.

Correct Answer: C. NH3

Ammonia (NH3) is a Lewis base because it has a lone pair of electrons to donate. The Lewis theory defines bases as electron pair donors rather than proton acceptors. This allows for the classification of substances as bases even without hydrogen.