Alloys — Set 3
Chemistry · मिश्र धातुएं · Questions 21–30 of 50
Which of the following elements is a non-metal often found in alloys?
Correct Answer: D. Carbon
Carbon is a non-metal that is a crucial component in alloys like steel and cast iron. It fits into the gaps between iron atoms, making the metal structure much harder and stronger. Pure carbon can exist as diamond or graphite in nature.
Which alloy is known for its high luster and is used for making mirrors in telescopes?
Correct Answer: C. Speculum metal
Speculum metal is a variation of bronze with a high tin content that can be polished to a mirror-like finish. Before glass mirrors were perfected, this alloy was the primary material for reflecting telescopes. It is very brittle and tarnishes easily compared to modern coatings.
Magnalium is an alloy primarily composed of Aluminum and which other metal?
Correct Answer: C. Magnesium
Magnalium contains roughly 5% to 15% magnesium mixed with aluminum. This addition makes the aluminum harder, more durable, and easier to machine. It is commonly used in laboratory balances and light-weight structural parts.
Which alloy is used in the manufacture of high-speed cutting tools?
Correct Answer: A. High-Speed Steel (HSS)
High-Speed Steel contains tungsten, molybdenum, and chromium to maintain hardness even at high temperatures. This allows the tools to cut other metals rapidly without losing their edge due to frictional heat. HSS replaced older carbon steels in industrial machining applications.
What is the purpose of adding Manganese to Steel?
Correct Answer: A. To increase hardness and strength
Manganese acts as a deoxidizer and helps increase the toughness and wear resistance of steel. It is essential in the production of high-strength steel used in railway tracks and heavy machinery. Manganese is also found naturally in the mineral pyrolusite.
Which alloy is widely used for making high-quality cutlery like forks and spoons?
Correct Answer: B. Stainless Steel
Stainless steel is preferred because it is hygienic, does not affect food flavor, and is resistant to staining. It is easy to clean and maintain, retaining its polished look for years. The '18/10' label on cutlery refers to the percentages of chromium and nickel.
Which of these is a copper-based alloy used for making statues and medals?
Correct Answer: A. Bronze
Bronze has been used for thousands of years to create durable statues because it expands slightly before setting, filling fine details of a mold. It develops a protective green layer called patina over time when exposed to the atmosphere. Bronze medals are traditionally awarded for third-place finishes.
What is the primary metal in the alloy 'Electrum'?
Correct Answer: B. Gold
Electrum is a naturally occurring alloy of gold and silver, often containing trace amounts of copper. It was used in ancient times to strike the first known coins in Lydia. The color of electrum ranges from pale to bright yellow depending on the gold content.
Constantan is an alloy of Copper and Nickel used for what purpose?
Correct Answer: D. Electrical resistance and thermocouples
Constantan is valued because its electrical resistivity remains constant over a wide range of temperatures. This property is crucial for precision resistors and temperature-sensing thermocouples. It typically consists of 55% copper and 45% nickel.
Which metal is the solvent in most Amalgams?
Correct Answer: A. Mercury
Mercury is considered the solvent because it is the liquid phase that dissolves the other metal solutes. Amalgams are unique because they can be formed without high-temperature melting. Because of its toxicity, mercury handling is strictly regulated in many industries.