Olympiad Test: Metals And Non-Metals - 1 - Class 8 MCQ

Introduction:
In this question, we are asked to identify a metal that exists in a liquid state. We are given four options: Gallium, Mercury, Sodium, and Potassium.
Explanation:
To determine the correct answer, let's evaluate each option:
1. Gallium:
- Gallium is a metal that has a melting point of 29.76°C (85.57°F) and a boiling point of 2204°C (3999°F). It exists in a solid state at room temperature and only becomes a liquid when heated.
- Therefore, Gallium is not the correct answer.
2. Mercury:
- Mercury is a metal that has a melting point of -38.83°C (-37.89°F) and a boiling point of 356.73°C (674.11°F). It exists in a liquid state at room temperature.
- Therefore, Mercury is the correct answer.
3. Sodium:
- Sodium is a metal that has a melting point of 97.72°C (207.9°F) and a boiling point of 883°C (1621°F). It exists in a solid state at room temperature and only becomes a liquid when heated.
- Therefore, Sodium is not the correct answer.
4. Potassium:
- Potassium is a metal that has a melting point of 63.38°C (146.08°F) and a boiling point of 759°C (1398°F). It exists in a solid state at room temperature and only becomes a liquid when heated.
- Therefore, Potassium is not the correct answer.
Conclusion:
Among the given options, Mercury is the metal that exists in a liquid state.

Answer:

Property regarding metal:

High melting and boiling point:
- Metals generally have high melting and boiling points compared to non-metals.
- This is because metal atoms are held together by strong metallic bonds, which require a large amount of energy to break.
- The strong metallic bonds are formed by the delocalized electrons moving freely throughout the metal lattice, creating a strong attraction between the positive metal ions and the negative electrons.
- The high melting and boiling points allow metals to be solid at room temperature and withstand high temperatures without easily changing their state.
- This property makes metals useful in applications that require high heat resistance, such as in construction materials, electrical wiring, and engine components.
Low melting and boiling point:
- This property is not applicable to metals. Metals generally have high melting and boiling points.
Low melting and high boiling point:
- This property is not applicable to metals. Metals generally have high melting and boiling points.
High melting and low boiling point:
- This property is not applicable to metals. Metals generally have high melting and boiling points.
Therefore, the correct property regarding metals is High melting and boiling point (Option A).

To identify the correct choice for metals, we need to understand their properties.
Metal Properties:
1. Ductility: The ability of a material to be stretched into a wire without breaking.
2. Malleability: The ability of a material to be hammered or rolled into thin sheets without breaking.
3. Brittleness: The tendency of a material to crack or break under stress.
Now, let's analyze each option:
Option A: Brittle and ductile
- This option is incorrect because it states that metals are both brittle and ductile, which is contradictory. Metals cannot be brittle and ductile simultaneously.
Option B: Malleable and ductile
- This option is the correct choice for metals because it correctly describes their properties. Metals are both malleable and ductile, meaning they can be shaped into thin sheets and stretched into wires.
Option C: Non-malleable and ductile
- This option is incorrect because it states that metals are not malleable but still ductile. However, metals cannot be ductile without being malleable.
Option D: Non-malleable
- This option is incorrect because it only describes the non-malleability of metals and does not mention their ductility.
In conclusion, the correct choice for metals is option B, which states that metals are malleable and ductile.

Answer:
Definition of Alloy:
An alloy is a substance composed of two or more metals, or a metal and a non-metal. It is a solid solution where the atoms of the different elements are uniformly distributed within the crystal lattice of the alloy.
Explanation:
When two or more metals are combined, they form an alloy. This combination can result in a substance with different properties compared to the individual metals. Alloys are widely used in various industries due to their desirable characteristics such as strength, durability, and resistance to corrosion.
Examples of Alloys:
Some common examples of alloys include:
1. Steel: an alloy of iron and carbon, with the addition of other elements such as chromium, nickel, and manganese.
2. Brass: an alloy of copper and zinc.
3. Bronze: an alloy of copper and tin.
4. Sterling silver: an alloy of silver and copper.
5. Stainless steel: an alloy of iron, chromium, and nickel.
Key Points:
- An alloy is a substance composed of two or more metals.
- Alloys can also be formed by combining a metal with a non-metal.
- Alloys have different properties compared to the individual metals.
- Common examples of alloys include steel, brass, bronze, sterling silver, and stainless steel.

Answer:
Introduction:
In this question, we are asked to identify which one of the given options is a metal. Let's analyze each option to determine the correct answer.
Options:
A: Gold
- Gold is a chemical element with the symbol Au and atomic number 79.
- It is a dense, soft, malleable, and ductile metal.
- Gold has a bright yellow color and is highly valued for its beauty and rarity.
- It is commonly used in jewelry, coins, and electronics.
B: Silver
- Silver is a chemical element with the symbol Ag and atomic number 47.
- It is a soft, white, lustrous transition metal.
- Silver has the highest electrical conductivity, thermal conductivity, and reflectivity of any metal.
- It is commonly used in jewelry, photography, and electrical contacts.
C: Aluminum
- Aluminum is a chemical element with the symbol Al and atomic number 13.
- It is a silvery-white, soft, nonmagnetic, and ductile metal.
- Aluminum is the third most abundant element in the Earth's crust and is widely used in various applications including packaging, construction, and transportation.
Conclusion:
From the analysis of the given options, we can conclude that all of these options (Gold, Silver, and Aluminum) are metals. Therefore, the correct answer is option D.

Non Metal: A non-metal is an element that does not have the characteristics of a metal. Non-metals are generally poor conductors of heat and electricity, have low melting and boiling points, and are usually brittle.
Options:
A: Copper - Copper is a metal and not a non-metal.
B: Chlorine - Chlorine is a non-metal. It is a highly reactive halogen gas.
C: Hydrogen - Hydrogen is a non-metal. It is a colorless, odorless gas.
D: Both (b) and (c) - This option is correct because both chlorine and hydrogen are non-metals.
Explanation:
To determine the correct answer, we need to identify which of the given options represents a non-metal.
- Copper is a metal, so option A is incorrect.
- Chlorine is a non-metal, so option B is correct.
- Hydrogen is a non-metal, so option C is correct.
Therefore, the correct answer is option D, which states that both chlorine and hydrogen are non-metals.

Metals generally form:
There are different types of oxides that metals can form, depending on their chemical properties. The options given are:
1. Basic oxides: These oxides are formed when metals react with oxygen. They are typically ionic compounds and have a basic pH. Examples include sodium oxide (Na2O) and calcium oxide (CaO).
2. Acidic oxides: These oxides are formed when non-metals react with oxygen. They are typically covalent compounds and have an acidic pH. Examples include carbon dioxide (CO2) and sulfur dioxide (SO2).
3. Neutral oxides: These oxides are formed when metals react with oxygen in a 1:1 ratio. They have a neutral pH and do not show any acidic or basic properties. Examples include copper(II) oxide (CuO) and iron(II) oxide (FeO).
Based on the given options, the correct answer is A: Basic oxides. Metals generally form basic oxides when they react with oxygen.
Remember to always follow the given rules and format your response in a visually appealing manner.

The element gallium is an unexpected metal—it's a soft, silvery-white metal that is solid at room temperature (similar to aluminum) but it can literally melt in the palm of your hand.

Lead has less metallic character, so it is a poor conductor of heat. Lead lies in group 14 of the modern periodic table. metallic characters decrease, as we move left to right in the periodic table. Metals are usually the best conductors of thermal energy. This is due to the way that metals are chemically bonded: metallic bonds (as opposed to covalent or ionic bonds) have free-moving electrons which are able to transfer thermal energy rapidly through the metal. Lead lacks this kind of electrons so it's a poor conductor of heat. But compared to non-metal it's conductivity is quite higher.

The Most Abundant Element in the Universe is Hydrogen.
Explanation:
Hydrogen is the most abundant element in the universe, making up about 75% of its elemental mass. Here's a detailed explanation of why hydrogen is the most abundant element:
1. Composition of the Universe:
- The universe is composed of various elements, including hydrogen, helium, oxygen, carbon, and many others.
- However, hydrogen is the most abundant element by far, comprising approximately 75% of the elemental mass in the universe.
2. Origin of the Universe:
- Hydrogen played a crucial role in the early stages of the universe's formation.
- After the Big Bang, the universe was primarily composed of hydrogen and helium.
- As the universe expanded and cooled, gravity started pulling hydrogen gas together, leading to the formation of stars and galaxies.
3. Role in Stellar Nucleosynthesis:
- Inside stars, nuclear fusion reactions occur, converting hydrogen into helium.
- This process releases a tremendous amount of energy, which powers the stars.
- In the stellar core, the temperature and pressure are high enough for hydrogen atoms to overcome their mutual repulsion and fuse together to form helium.
4. Abundance in Galaxies:
- The abundance of hydrogen is not only limited to our Milky Way galaxy but is observed in other galaxies as well.
- Hydrogen gas clouds are found in vast quantities within galaxies, serving as the fuel for star formation.
5. Presence in Interstellar Medium:
- The interstellar medium, the space between stars, also contains a significant amount of hydrogen.
- It exists in molecular clouds and diffuse gas, providing the raw material for the formation of new stars and planetary systems.
In conclusion, hydrogen is the most abundant element in the universe due to its prevalence in the early universe, its role in stellar nucleosynthesis, and its presence in galaxies and the interstellar medium.