Everyday Chemistry — Set 2
Chemistry · रोजमर्रा का रसायन · Questions 11–20 of 50
Which polymer is widely used to make disposable coffee cups and packaging foam?
Correct Answer: A. Polystyrene
Polystyrene is a lightweight plastic that acts as an excellent thermal insulator. It is often expanded with gas to create the familiar white foam used in shipping. However, it is a concern for environmentalists because it does not biodegrade easily.
Which chemical is commonly used in the 'breathalyzer' test to detect alcohol?
Correct Answer: D. Potassium Dichromate
Potassium dichromate reacts with ethanol in the breath, causing a color change from orange to green. This chemical reaction allows traffic police to estimate blood alcohol levels. The change in color intensity is proportional to the concentration of alcohol present.
Which of the following is used as an artificial sweetener with zero calories?
Correct Answer: B. Aspartame
Aspartame is an intense sweetener that is about two hundred times sweeter than table sugar. It is used in diet sodas and sugar-free foods to provide sweetness without adding calories. It is composed of two amino acids but is not suitable for high-temperature cooking.
Which chemical is the main component of 'plaster of Paris'?
Correct Answer: A. Calcium Sulfate Hemihydrate
Plaster of Paris is made by heating gypsum to a specific temperature to remove most of its water. When mixed with water again, it hardens into a solid mass within minutes. It is extensively used in medicine for bone casts and in interior decoration.
Which acid is present in the sting of ants and bees?
Correct Answer: C. Formic Acid
Formic acid is injected by ants and bees during a sting, causing irritation and pain. It is the simplest carboxylic acid and was historically obtained by distilling ants. Neutralizing the area with a mild base like baking soda can provide relief.
Which gas is released when baking soda is mixed with vinegar?
Correct Answer: B. Carbon Dioxide
Carbon dioxide gas is produced as a byproduct of the neutralization reaction between the base and acid. This bubbling effect is used in baking to make cakes and bread rise. It is also a popular reaction for school-level science experiments.
Which material is used as the 'lead' in modern pencils?
Correct Answer: B. Graphite
Pencil 'lead' is actually a mixture of graphite and clay. Graphite is an allotrope of carbon that leaves a grey mark because its layers slide off onto paper. Despite the name, no actual lead metal has been used in pencils for centuries.
Which chemical compound is used as a refrigerant in older refrigerators and air conditioners?
Correct Answer: C. Chlorofluorocarbons
Chlorofluorocarbons were preferred for their stability and lack of toxicity near humans. However, their use was phased out because they cause significant damage to the Earth's ozone layer. Modern cooling systems now use more environmentally friendly alternatives.
Which of the following is used in the vulcanization of rubber to make it harder?
Correct Answer: C. Sulfur
Sulfur is heated with natural rubber to create cross-links between the polymer chains. This process makes the rubber more durable, elastic, and resistant to temperature changes. Charles Goodyear is credited with discovering this method in the nineteenth century.
Which substance is commonly used to purify swimming pool water by killing bacteria?
Correct Answer: D. Chlorine
Chlorine is a powerful disinfectant that effectively eliminates harmful pathogens in water. It is usually added in the form of liquid sodium hypochlorite or solid calcium hypochlorite. Regular testing is required to maintain the correct concentration for safety.