Test: Metals In Nature - Class 10 MCQ

Answer:
The alloy that has copper as its constituent is Brass.
Explanation:
Brass is an alloy composed of copper and zinc. It is commonly used in various applications due to its desirable properties such as its high corrosion resistance, low friction, and excellent electrical conductivity. Here is a detailed explanation of the given options:
- Brass: Brass is an alloy of copper and zinc. It is widely used in musical instruments, plumbing fittings, decorative items, and electrical connectors.
- Alnico: Alnico is an alloy of aluminum, nickel, and cobalt. It is known for its strong magnetic properties and is commonly used in magnets and electric guitar pickups.
- Steel: Steel is an alloy of iron and carbon, with small amounts of other elements. Copper is not a constituent of steel.
- Solder: Solder is an alloy used for joining metals together. It typically consists of tin and lead, and sometimes contains small amounts of other metals. Copper is not a constituent of solder.
Therefore, the correct answer is option A: Brass.

Which of the following does not corrode?

Answer: B. Stainless steel

Explanation:

Corrosion is the process of deterioration of a material due to chemical reactions with the environment. Some metals are more prone to corrosion than others.

Corrosion of Metals:

• Silver: Silver is a noble metal and is highly resistant to corrosion.


• Stainless Steel: Stainless steel is an alloy of iron, chromium, and other elements. It is known for its corrosion-resistant properties.


• Copper: Copper is susceptible to corrosion, especially in the presence of moisture and certain atmospheric conditions.


• Iron: Iron is prone to corrosion and forms iron oxide, commonly known as rust, when exposed to oxygen and moisture.

Therefore, the metal that does not corrode is stainless steel. It is specifically designed to resist corrosion and is widely used in various applications where corrosion resistance is required.

Solder is an alloy of:
A: Lead and tin
- Solder is commonly made by combining lead and tin in various proportions.
- Lead makes up the majority of the alloy, typically ranging from 50% to 70%, while tin accounts for the remainder.
- Lead provides the solder with its low melting point and malleability, allowing it to be easily melted and shaped.
- Tin improves the solder's strength and corrosion resistance.
B: Copper and zinc
- Copper and zinc are not commonly used together to make solder. They are typically used to create brass, which is a different alloy.
C: Copper and tin
- Copper and tin are used together to create bronze, which is a different alloy. Bronze is primarily used for casting, not for soldering.
D: Iron and copper
- Iron and copper are not commonly used together to make solder. They have different melting points and properties that are not suitable for soldering purposes.
Therefore, the correct answer is A: Lead and tin.

Ruthenium and paltinum are noble metals beacause they do not react with other substances and found in their pure forms.

The alloy of iron, chromium, and nickel is called stainless steel. Here is a detailed explanation of why stainless steel is the correct answer:
Definition:
Stainless steel is a type of alloy that is corrosion-resistant and contains a minimum of 10.5% chromium. It also typically includes other elements such as iron, nickel, and sometimes molybdenum.
Composition:
Stainless steel is primarily composed of the following elements:
- Iron: It forms the base of the alloy and provides strength.
- Chromium: It is the essential element that makes stainless steel resistant to corrosion and adds durability.
- Nickel: It enhances the corrosion resistance of stainless steel and provides stability at high temperatures.
Properties:
Stainless steel has several unique properties, including:
- Corrosion resistance: The high chromium content forms a protective layer on the surface, preventing rust and corrosion.
- Strength: Stainless steel is known for its strength and durability.
- Heat resistance: It can withstand high temperatures, making it suitable for various applications.
- Hygienic: Stainless steel is non-porous and easy to clean, making it ideal for use in food processing and medical industries.
Applications:
Stainless steel is widely used in various industries and applications, such as:
- Kitchenware and appliances: Cutlery, cookware, sinks, and refrigerators.
- Construction: Building facades, bridges, and structural components.
- Automotive: Exhaust systems, trim, and decorative parts.
- Medical: Surgical instruments, implants, and equipment.
- Aerospace: Aircraft components and structures.
In conclusion, stainless steel is the correct answer as it is an alloy of iron, chromium, and nickel and possesses unique properties that make it highly versatile and widely used in various industries.

To determine the purity of pure gold in carat, we need to consider the carat system used to measure the purity of gold. The carat system is a scale used to measure the purity of gold and is denoted by the abbreviation "ct" or "K".
Here are the different carat values and their corresponding purity levels:
1. 24 carat: This is considered pure gold, with a purity level of 99.9%. It is the highest level of purity in the carat system.
2. 22 carat: This is the most common carat value used for gold jewelry. It has a purity level of 91.7%, which means it contains 22 parts of gold and 2 parts of other metals.
3. 23 carat: This carat value is less common and has a purity level of 95.8%. It contains 23 parts of gold and 1 part of other metals.
4. 21 carat: This carat value is also less common and has a purity level of 87.5%. It contains 21 parts of gold and 3 parts of other metals.
Therefore, the correct answer is: A: 24 carat, which represents pure gold with a purity level of 99.9%.

alloying a metal ,its properties not degrade but they show the upgrade qualities like high tensile strength,lustrous etc .New substance formed by the alloying ,like brass is the result of alloying.

Answer:
The metal that is always a constituent of an amalgam is Mercury.
Explanation:
Amalgam is a type of alloy that is formed by combining mercury with one or more other metals. It is commonly used in dentistry for dental fillings. Here is a detailed explanation:
- What is an amalgam?
- An amalgam is a mixture or alloy of mercury with another metal or metals.
- It is typically a solid material that has a silver-like appearance.
- Why is mercury always a constituent of an amalgam?
- Mercury plays a crucial role in the formation and properties of amalgams.
- It acts as a "binder" or "matrix" that holds the other metals together.
- Mercury has the ability to form a liquid phase, allowing it to mix and react with other metals.
- Other metals commonly used in amalgams:
- While mercury is always present in an amalgam, the other metal(s) can vary.
- Common metals used in dental amalgams include silver, tin, copper, and zinc.
- The specific combination of metals used in an amalgam depends on the desired properties and application.
- Properties and uses of amalgams:
- Amalgams are known for their strength, durability, and resistance to corrosion.
- They have been widely used in dentistry for dental fillings due to their ability to withstand the forces of chewing.
- Amalgams are also used in various other applications, such as electrical contacts and mirrors.
In conclusion, while mercury is always a constituent of an amalgam, the other metal(s) can vary depending on the desired properties and application.

Answer:
Galvanization:
Galvanization is a process of coating iron or steel with a protective layer of zinc to prevent corrosion. This is done by immersing the metal in a bath of molten zinc or by electroplating the metal with zinc.
Coating:
The coating in galvanization is a layer of another metal that is applied to the surface of the iron or steel. In this case, the coating material is zinc.
Benefits of Zinc Coating:
The application of a zinc coating offers several advantages, including:
1. Corrosion Resistance: Zinc acts as a sacrificial anode, meaning it corrodes before the iron or steel beneath it. This protects the underlying metal from rust and corrosion.
2. Durable Protection: The zinc coating provides long-lasting protection against the elements, making it suitable for outdoor applications.
3. Self-Healing: Even if the zinc coating is scratched or damaged, it can still provide protection. The exposed zinc reacts with oxygen and moisture in the air to form a protective layer called zinc oxide.
4. Aesthetic Appeal: Zinc coatings can be left as a shiny, silver-colored finish or can be further treated to achieve a desired appearance.
Conclusion:
In galvanization, iron or steel is coated with a layer of zinc. This zinc coating provides corrosion resistance, durability, and aesthetic appeal to the metal.

Minerals from which metals are extracted are called:

The correct answer is C: Ores.

Explanation:

Metals are extracted from minerals in the earth's crust. These minerals are known as ores. Ores are rocks that contain a high enough concentration of a particular metal to be economically viable for extraction. Different types of ores are found in different locations and contain different metals.

Here are some key points to understand:

- Ores are the source of metals.
- Ores are rocks that contain a high concentration of a particular metal.
- Ores are economically viable for extraction.
- Different types of ores contain different metals.
- Metals are extracted through various processes such as mining, smelting, and refining.
- Ores undergo processing to separate the metal from other elements and impurities.
- The extracted metal can then be used for various purposes, such as manufacturing, construction, and energy production.

It is important to note that not all minerals are ores. Some minerals may have industrial or aesthetic value but may not contain a high enough concentration of a metal to be considered economically viable for extraction.

Chlorine os the second halogen, being a non - metal in group 17 of the periodic table. It's not a half metal because it is a now metal.

Anodising is a process of forming a thick oxide layer of aluminum. This aluminium oxide coat makes it resistant to further corrosion.

An alloy is a homogenous mixture of two or more metals or non metals mixed in a molten state.

Obviously copper and zinc is the right one. copper percentage in the mixture of brass is 73% and and the zinc percentage in the mixture of brass is 25%.To enhance the machinability of brass, lead is often added in concentrations of around 2%.

The silver article becomes black after sometimes when exposed to air because silver reacts with sulphur which is present in the atmosphere and then forms silver sulphide. Thus the layer of this silver sulphide is formed on the surface of the silver article so they appear as dull or black.