Man-Made Materials — Set 3
Chemistry · मानव निर्मित सामग्री · Questions 21–30 of 50
Which process is used to make soaps from fats or oils and sodium hydroxide?
Correct Answer: C. Saponification
Saponification is the chemical reaction where an ester is heated with an alkali to produce soap and glycerol. Sodium soaps are generally hard, while potassium soaps are soft or liquid. This process has been used for centuries to create cleaning agents.
Detergents are better than soaps for laundry in hard water because?
Correct Answer: C. They do not form insoluble scum
Soaps react with calcium and magnesium ions in hard water to form an insoluble precipitate called scum. Detergents contain sulfonates that remain soluble even in the presence of these ions. This allows detergents to maintain their cleaning efficiency in any water type.
What is the chemical name for the explosive commonly known as TNT?
Correct Answer: C. Trinitrotoluene
Trinitrotoluene is a stable explosive that requires a detonator to explode. It is widely used in military and industrial applications due to its safety in handling. It is produced by the nitration of toluene.
Which chemical is often used as a 'fixing agent' in the manufacturing of ink?
Correct Answer: A. Tannic acid
Tannic acid reacts with iron salts to produce a permanent black color in traditional inks. It helps the ink bind to the paper fibers and resist fading over time. Modern inks use a variety of synthetic dyes and polymers for similar effects.
Which substance is used to provide a red color to fireworks?
Correct Answer: A. Strontium salts
Strontium salts emit a characteristic deep red light when they are heated in a flame. Different metal ions are used in pyrotechnics to achieve various colors. For example, barium produces green and copper produces blue.
The chemical used for the 'artificial ripening' of green fruits is?
Correct Answer: D. Ethylene
Ethylene is a natural plant hormone that triggers the ripening process in fruits. In commercial practice, calcium carbide is often used to produce acetylene, which mimics ethylene's effect. However, the direct use of ethylene gas is considered safer and more controlled.
Which of the following is a bio-polymer produced by living organisms?
Correct Answer: A. Starch
Starch is a natural polymer made of glucose units produced by plants for energy storage. Unlike synthetic polymers, it is fully biodegradable and breaks down into harmless substances. Cellulose and proteins are other examples of natural bio-polymers.
Which synthetic chemical is most commonly added as a preservative in packaged foods like soft drinks and fruit juices to inhibit microbial growth?
Correct Answer: A. Sodium Benzoate
Sodium benzoate (C6H5COONa) is the most widely used synthetic food preservative, particularly in acidic foods like soft drinks, fruit juices, and pickles. It works by inhibiting the growth of bacteria, molds, and yeasts. It is effective at a pH below 4.5 where it converts to benzoic acid. Sodium chloride (common salt) and acetic acid (vinegar) are traditional preservatives, while citric acid acts as both a preservative and flavouring agent. Sodium benzoate is approved by FSSAI and Codex Alimentarius for use in specified food categories.
What is the main component of 'LPG' used as a domestic fuel?
Correct Answer: B. Propane and Butane
Liquefied Petroleum Gas consists primarily of butane and propane which are easily liquefied under pressure. It is clean-burning and provides high heat energy for cooking. A small amount of ethyl mercaptan is added to detect leaks by its strong smell.
Which material is used for the coating of 'matchstick' heads?
Correct Answer: A. Antimony trisulfide and Potassium chlorate
The correct answer is 'Antimony trisulfide and Potassium chlorate'. The match head contains an oxidizing agent and a fuel that ignites when rubbed against a striking surface. Red phosphorus is located on the side of the matchbox, not the stick head, for safety. When struck, the friction converts some red phosphorus to white, which ignites the head.