Acids & Bases — Set 4

Correct Answer: B. Carbon dioxide

The reaction between baking soda and vinegar releases carbon dioxide gas as effervescence. This reaction is commonly used in fire extinguishers and for making cakes fluffy. The gas can be tested by passing it through lime water, which turns milky.

Correct Answer: D. 7

Pure water is neutral and has a pH of exactly 7 at 25°C. At this point, the concentration of H+ and OH- ions is perfectly balanced. Even slight impurities in water can change its pH value.

Correct Answer: A. Turns red litmus blue

Bases have a bitter taste and turn red litmus paper blue. They also have a soapy or slippery feel when touched by fingers. Many common household cleaners like bleach and soap are basic in nature.

Correct Answer: A. Acetic acid

Acetic acid in the form of vinegar is used to preserve pickles by inhibiting bacterial growth. The acidic environment prevents food spoilage and enhances the shelf life. It also adds a tangy flavor to the preserved food.

Correct Answer: C. Vinegar

Since a wasp sting is alkaline, a mild acid like vinegar is used to neutralize it. This reduces the pain and swelling caused by the venom. Bee stings, conversely, are acidic and require a basic treatment like baking soda.

Correct Answer: B. Acidic

Non-metal oxides like carbon dioxide and sulfur dioxide are acidic in nature. They react with water to form acids, such as carbonic acid or sulfuric acid. This property is the primary cause of acid rain in polluted areas.

Correct Answer: B. Ammonium hydroxide

Ammonium hydroxide is effective at removing grease and stains without leaving streaks on glass. It is a weak base and evaporates quickly, making it ideal for window cleaners. It has a very strong and distinct ammonia smell.

Correct Answer: D. Aluminum oxide

Aluminum oxide is amphoteric because it can react with both acids and bases. It shows both acidic and basic characteristics depending on the reacting substance. Zinc oxide is another common example of an amphoteric oxide.

Correct Answer: C. HNO3

HNO3 is the chemical formula for nitric acid, a highly corrosive mineral acid. It is used in the production of fertilizers like ammonium nitrate and in explosives. In pure form, it is colorless but can turn yellow over time.

Correct Answer: D. Phenolphthalein

Phenolphthalein is a synthetic chemical indicator that is colorless below pH 8.2. It turns a vibrant pink or fuchsia color in basic environments. It is frequently used in chemistry labs for precise titration experiments.