Alloys

1. Which one of the following metals is mixed with gold to provide streng

Which one of the following metals is mixed with gold to provide strength to the jewellery?

Manganese
Mica
Aluminium
Copper
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UPSC CISF-AC-EXE – 2022
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Pure gold (24 carat) is very soft and malleable, making it unsuitable for crafting durable jewellery. It is typically alloyed with other metals to increase its hardness and strength. Copper is a common metal used for this purpose, along with silver, nickel, and zinc.
– Alloying increases the durability and wear resistance of gold jewellery.
– The caratage of gold indicates the proportion of pure gold in the alloy (e.g., 18K gold is 75% gold).
The choice of alloying metal also affects the colour of the gold. For example, copper gives a reddish tint (rose gold), while silver and palladium create white gold.

2. Which one of the following statements is correct?

Which one of the following statements is correct?

Alloys are mixtures.
Alloys are compounds.
Alloys are always made up of metals.
All alloys contain carbon as one of their components.
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UPSC CAPF – 2023
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An alloy is a metallic substance composed of two or more elements, at least one of which is a metal. It is typically formed by mixing molten components. Alloys are considered mixtures because their constituent elements are not chemically bonded in a fixed ratio throughout the material; their properties are a combination of the properties of the constituents, and they can often be separated by physical means. Option B is incorrect as alloys are mixtures, not compounds. Option C is incorrect as alloys can include non-metals (like carbon in steel). Option D is incorrect as many alloys do not contain carbon (e.g., brass is copper and zinc).
Alloys are physical mixtures of metals or metals and non-metals.
The properties of alloys often differ significantly from those of their constituent elements. For example, steel (iron and carbon) is much stronger than pure iron, and brass (copper and zinc) is harder than either copper or zinc.

3. White gold is an alloy of

White gold is an alloy of

gold, nickel and palladium
gold, cobalt and palladium
gold, titanium and platinum
gold, magnesium and palladium
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UPSC CAPF – 2022
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White gold is an alloy of gold with at least one white metal. The purpose of alloying gold with white metals is to produce a white appearance and often increase its hardness and durability. Common white metals used in white gold alloys include nickel, palladium, silver, and platinum.
– Nickel is a common and inexpensive white metal used in white gold alloys, especially in the United States. It provides hardness but can cause allergic reactions in some individuals.
– Palladium is a more expensive white metal used in white gold alloys, particularly in Europe. It produces a whiter alloy and is hypoallergenic.
– Platinum is also a white metal and can be used, often as part of a platinum group metal mix including palladium.
– Silver is a white metal sometimes used in smaller quantities to modify color and workability.

Option A lists gold, nickel, and palladium, which are all standard components found in various white gold alloys.
Option B lists cobalt, which is less commonly used than nickel or palladium in standard white gold jewelry alloys.
Option C lists titanium, which is not typically used in gold alloys for jewelry purposes.
Option D lists magnesium, which is also not typically used in gold alloys for jewelry purposes.

Therefore, gold, nickel, and palladium represent a typical composition of white gold alloys.

– White gold is an alloy of gold with white metals.
– Common white metals alloyed with gold include nickel, palladium, silver, and platinum.
– Option A correctly lists common alloying metals for white gold.
The actual composition of white gold varies. Nickel-white gold alloys are typically 10-20% nickel, with possibly some copper or zinc. Palladium-white gold alloys are typically 10-20% palladium, which is more expensive but produces a softer, more easily worked, and hypoallergenic alloy. Higher karat white gold alloys often use palladium. White gold jewelry is usually plated with rhodium to give it a brighter white finish.

4. Bronze is an alloy of copper and

Bronze is an alloy of copper and

nickel
iron
tin
aluminium
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UPSC CAPF – 2017
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Bronze is an alloy of copper and tin.
– An alloy is a mixture of metals, or a mixture of a metal and another element.
– Bronze is historically one of the most important alloys, known for its hardness and durability compared to pure copper.
– Typically, bronze consists primarily of copper, usually with tin as the main additive. The amount of tin varies but is commonly between 5% and 20%.
Brass is another common copper alloy, primarily consisting of copper and zinc. Other elements like aluminum, manganese, phosphorus, or silicon may be added to bronze to achieve specific properties, but tin is the defining secondary element for classical bronze.

5. Which one of the following metal is NOT an essential component in stai

Which one of the following metal is NOT an essential component in stainless steel ?

Iron
Nickel
Chromium
Tin
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UPSC NDA-2 – 2023
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D) Tin is NOT an essential component in stainless steel.
– Stainless steel is primarily an alloy based on Iron (Fe).
– The key element that provides its characteristic corrosion resistance (β€œstainless” property) is Chromium (Cr), which must be present in a minimum amount (typically 10.5% by mass). Chromium forms a passive, protective oxide layer on the surface.
– Nickel (Ni) is another common and essential alloying element in many widely used types of stainless steel, particularly austenitic stainless steels (like the 300 series, e.g., 304 and 316). Nickel enhances corrosion resistance, strength, and ductility.
– Iron, Chromium, and often Nickel are the primary essential metallic components of stainless steel. Other elements like Carbon (controlled for strength and ductility), Manganese, Silicon, Molybdenum (for increased corrosion resistance), etc., are also present, but Iron, Chromium, and Nickel are central to its structure and properties.
– Tin (Sn) is not typically used as an alloying element in stainless steel. It is used in other alloys (like bronze, pewter, solder) or as a coating (tin plating), but it is not considered an essential component of stainless steel formulations.

6. Which one of the following alloys contains a non-metal as one of its c

Which one of the following alloys contains a non-metal as one of its constituent ?

Brass
Bronze
Amalgam
Steel
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UPSC NDA-2 – 2023
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Steel is an alloy that contains a non-metal, Carbon, as one of its primary constituents.
An alloy is a mixture of metals or a mixture of a metal and another element. Brass is an alloy of copper and zinc (both metals). Bronze is typically an alloy of copper and tin (both metals). An amalgam is an alloy of mercury with another metal (both mercury and the other element are metals). Steel is primarily an alloy of iron and carbon, where carbon is a non-metal. The carbon content in steel ranges from about 0.2% to 2.1% by weight.
The presence of carbon significantly alters the properties of iron, increasing its strength and fracture resistance compared to pure iron. The amount of carbon affects the steel’s properties; for instance, higher carbon content generally leads to harder and stronger steel but also makes it more brittle.

7. Bronze is an alloy of

Bronze is an alloy of

Cu and Zn
Cu and Sn
Zn and Mg
Fe and Cu
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UPSC NDA-2 – 2022
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Bronze is an alloy of copper (Cu) and tin (Sn).
Alloys are mixtures of metals, or a mixture of a metal and another element. Bronze is historically significant and known for its hardness and durability.
Common metal alloys include:
– Brass: Copper (Cu) and Zinc (Zn)
– Bronze: Copper (Cu) and Tin (Sn)
– Stainless Steel: Iron (Fe), Chromium (Cr), Nickel (Ni), and Carbon (C)
– Solder: Tin (Sn) and Lead (Pb)

8. Solder is an alloy of

Solder is an alloy of

Cu and Sn.
Fe and Zn.
Pb and Sn.
Ag and Zn.
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UPSC NDA-1 – 2021
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Solder is typically an alloy of lead (Pb) and tin (Sn).
Traditional solder, widely used for joining metals in plumbing and electronics, is an alloy primarily composed of lead and tin. The ratio of lead to tin affects the melting point and properties of the solder. Common compositions include 60% tin and 40% lead, or the eutectic alloy of 63% tin and 37% lead which has the lowest melting point.
Due to environmental concerns about lead toxicity, lead-free solders have become increasingly popular, especially in electronics. Lead-free solders often consist mainly of tin alloyed with other metals like silver (Ag), copper (Cu), and sometimes bismuth (Bi) or antimony (Sb). However, without specifying β€œlead-free”, the standard Pb-Sn alloy is implied.

9. Bronze is an alloy of:

Bronze is an alloy of:

copper and tin.
copper and zinc.
zinc and tin.
copper and lead.
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UPSC Geoscientist – 2021
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Bronze is traditionally and most commonly an alloy of copper and tin. The addition of tin to copper increases its hardness and durability, making it suitable for various applications like tools, weapons, and statues.
Bronze is an alloy primarily composed of copper and tin.
Brass is another common copper alloy, but it is an alloy of copper and zinc. Different types of bronze may contain other elements like phosphorus, manganese, aluminum, or silicon, but the primary components are copper and tin.

10. What are the constituents of alloy solder ?

What are the constituents of alloy solder ?

Pb and Zn
Pb and Sn
Pb and Si
Pb and Co
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UPSC CDS-2 – 2021
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Solder is a fusible metal alloy used for joining materials by melting the solder and causing it to flow into the joint. The most common type of solder used in electronics and plumbing is a eutectic alloy of tin (Sn) and lead (Pb). While lead-free solders using tin alloys with silver or copper are now common due to environmental concerns regarding lead, traditional and historically significant solders are alloys of lead and tin. Among the given options, Pb and Sn are the constituents of common solder.
– Solder is a metal alloy used for joining metals.
– Common solder alloys primarily consist of tin and lead.
The melting point of solder is lower than that of the metals being joined, allowing it to melt and bond without melting the base metals. The ratio of tin to lead affects the melting point and properties of the solder. Eutectic solder (63% Sn, 37% Pb) has a single melting point, whereas non-eutectic solders melt over a range of temperatures.
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