Acids & Bases — Set 2
Chemistry · अम्ल और क्षार · Questions 11–20 of 60
What happens during a neutralization reaction?
Correct Answer: A. An acid and a base form salt and water
In neutralization, the H+ ions of an acid react with OH- ions of a base to form water and a salt. This reaction is generally exothermic, meaning it releases heat energy. It is a fundamental concept used in treating indigestion and soil acidity.
Which base is used in the manufacturing of soap?
Correct Answer: D. Sodium hydroxide
Sodium hydroxide, also known as caustic soda, is used in the saponification process to make soap. It reacts with fats or oils to produce soap and glycerol. Potash or potassium hydroxide is also used for making liquid soaps.
Which acid is produced in the human stomach to help in digestion?
Correct Answer: D. Hydrochloric acid
Hydrochloric acid is secreted by the gastric glands to create an acidic environment for enzymes. It helps break down food and kills harmful bacteria that may enter with the meal. A mucus lining protects the stomach walls from being damaged by this acid.
What is the common name for Calcium Hydroxide?
Correct Answer: A. Slaked lime
Calcium hydroxide is commonly known as slaked lime and is produced by adding water to quicklime. It is used in whitewashing buildings and in the purification of sewage water. It is a moderately strong base that is slightly soluble in water.
Which indicator is prepared from a common kitchen spice and turns reddish-brown in bases?
Correct Answer: D. Turmeric
Turmeric is a natural indicator that stays yellow in acidic solutions but turns reddish-brown in basic ones. This is why a curry stain on a white shirt turns red when soap is applied. It is one of the most easily accessible natural indicators.
Which of the following substances has a pH value greater than 10?
Correct Answer: C. Sodium hydroxide solution
Sodium hydroxide is a strong base, and its concentrated solutions have a pH close to 14. Blood is slightly basic with a pH of about 7.4, while lemon juice is acidic. Substances with high pH values are corrosive to organic tissues.
According to the Arrhenius theory, what do acids produce in water?
Correct Answer: A. Hydrogen ions
Arrhenius defined acids as substances that increase the concentration of H+ ions when dissolved in water. These hydrogen ions usually exist as hydronium ions (H3O+) in aqueous solutions. This theory provides the basis for understanding the pH scale.
Which acid is found in tamarind and grapes?
Correct Answer: C. Tartaric acid
Tartaric acid is a white crystalline organic acid occurring naturally in many fruits like grapes and tamarind. It is used as an antioxidant in food and to give a sour taste to candies. It is also an important ingredient in baking powder.
What is the nature of metal oxides generally?
Correct Answer: B. Basic
Most metal oxides are basic in nature and react with water to form bases or with acids to form salts. For example, magnesium oxide reacts with water to produce magnesium hydroxide. Non-metal oxides, on the other hand, are typically acidic.
Which of the following is an olfactory indicator?
Correct Answer: A. Onion
Onion is an olfactory indicator because its characteristic smell changes when it is mixed with a base. Such indicators are useful for visually impaired students in laboratories. Vanilla essence and clove oil are other common olfactory indicators.