All questions of Materials Around Us for Class 6 Exam

Mass is the quantity of matter in an object, measured in grams (g) or kilograms (kg).

Mass is the measure of the amount of matter in an object, typically measured in grams or kilograms.

Understanding Opaque Materials
Opaque materials are substances that do not allow light to pass through them. This characteristic is essential in various applications, from construction to art. Let’s delve into why wood is considered an opaque material.
Characteristics of Opaque Materials
- Light Blockage: Opaque materials prevent the transmission of light. When light hits these substances, it is either absorbed or reflected, making it impossible to see through them.
- Examples: Common examples include metals, ceramics, and dense materials like wood.
Analysis of the Options
- Clear Plastic: This is a transparent material, allowing light to pass through easily.
- Frosted Glass: While frosted glass scatters light and is not clear, it still allows some light to penetrate, making it semi-opaque rather than fully opaque.
- Wood: This material is solid and does not permit any light to pass through. Thus, it is a classic example of an opaque material.
- Transparent Glass: As the name implies, this material is clear and allows light to pass through unobstructed.
Conclusion
In summary, option 'C' (Wood) is the correct answer because it fully blocks light, making it an opaque material. Understanding the classification of materials based on their interaction with light is crucial for recognizing their uses in everyday life.

Understanding Transparency
Transparency is a key property that indicates how clearly we can see through a material. It plays a crucial role in various applications, from everyday objects to scientific instruments.
What is Transparency?
- Transparency refers to the ability of a material to allow light to pass through it without significant scattering.
- Materials can be categorized based on their transparency:
- Transparent: Clear materials like glass and clear plastics that allow light to pass through unobstructed.
- Translucent: Materials like frosted glass or certain plastics that allow some light to pass but scatter it, making objects behind them unclear.
- Opaque: Materials like wood or metals that do not allow light to pass through at all.
Importance of Transparency
- Vision and Safety: Transparent materials are crucial for windows in buildings and vehicles, providing visibility while ensuring safety.
- Science and Technology: In laboratories, transparent containers and equipment allow scientists to observe reactions and processes clearly.
- Art and Design: Artists often use transparent materials to create visually appealing effects in their work.
Conclusion
Understanding transparency helps us choose the right materials for specific purposes. It is essential for enhancing visibility and functionality in various fields, making it a fundamental property to consider.

Soluble materials, like sugar and salt, dissolve completely in water, making them invisible.

Sand does not dissolve in water, unlike sugar and salt. It remains visible even after stirring.

Sugar dissolves in water, forming a solution, while sand, chalk, and clay do not dissolve in water.

Oil is less dense than water, so it floats on top instead of mixing.

Understanding Material Selection
When creating objects, the choice of material is crucial because different materials possess unique properties that make them suitable for specific functions. Here’s a detailed explanation of why this is important.
Specific Properties of Materials
- Strength: Some materials, like metals, are strong and can withstand heavy loads. This makes them ideal for construction and machinery.
- Weight: Lightweight materials, such as plastics and aluminum, are preferred for items like airplanes and packaging to improve efficiency and reduce energy consumption.
- Durability: Certain materials resist wear and tear better than others. For example, rubber is used for tires because it can withstand friction and impacts.
- Conductivity: Materials like copper are excellent conductors of electricity, making them essential for wiring and electrical components.
- Insulation: Materials such as foam or fiberglass are used for insulation because they can trap air and reduce heat transfer.
Suitability for Different Purposes
- Functionality: The intended use of an object dictates the choice of material. For instance, kitchen utensils need to be heat-resistant and easy to clean, leading to the use of stainless steel or silicone.
- Aesthetic Appeal: While functionality is key, the appearance of materials also matters. Wood, glass, and ceramics can provide beauty and elegance to furniture and decor.
- Cost and Availability: Economic factors also influence material selection. Common and affordable materials are often chosen to keep costs down while meeting quality standards.
In conclusion, each material's specific properties make it suitable for different uses, ensuring that objects perform effectively and meet the required standards. This careful selection process reflects the diverse needs of society and enhances the functionality of everyday items.

Material Used for Making Windows: Glass
Glass is commonly used for making windows because of its transparency and durability. Let's explore why glass is the preferred material for windows:

Transparency:
- Glass is transparent, allowing natural light to enter a space and providing a clear view of the outside.
- This transparency creates a sense of openness and connection to the surroundings.

Durability:
- Glass is a durable material that can withstand various weather conditions, including rain, wind, and sunlight.
- It is also resistant to scratches and does not deteriorate easily over time.

Insulation:
- Glass windows can be designed to provide thermal insulation, helping to maintain a comfortable indoor temperature.
- Double or triple-pane glass windows with gas fills can enhance energy efficiency by reducing heat loss.

Aesthetics:
- Glass windows come in various styles, sizes, and designs, allowing for customization to complement the architectural style of a building.
- They can enhance the visual appeal of a space and create a modern and sleek look.

Ease of Maintenance:
- Glass windows are relatively easy to clean and maintain compared to other materials like wood or metal.
- Regular cleaning with a glass cleaner can keep windows looking clear and sparkling.
In conclusion, the transparency, durability, insulation properties, aesthetics, and ease of maintenance make glass the ideal material for making windows in buildings. Its versatility and functionality have made it a popular choice among architects, builders, and homeowners.

The Property of Hardness in Materials
The hardness or softness of a material is fundamentally determined by its physical properties, particularly its ability to resist deformation. This characteristic is often assessed through its ability to be compressed or scratched.
Key Factors Influencing Hardness
- Resistance to Scratching: Hard materials, like diamonds, have a high resistance to scratching due to their tightly packed atomic structure. Conversely, soft materials, like talc, can be easily scratched or deformed.
- Ability to Be Compressed: Materials that can be easily compressed or deformed under pressure are typically considered soft. For instance, rubber can be squished and molded easily, indicating its softness.
- Atomic Structure: The arrangement of atoms in a material greatly affects its hardness. Hard materials tend to have strong atomic bonds that require significant force to break, while soft materials have weaker bonds.
Comparison of Options
- a) Amount of Water Absorbed: While water absorption can indicate porosity, it doesn't directly determine hardness.
- b) Appearance: The way a material looks does not reflect its hardness. For example, a shiny surface can be either hard or soft.
- d) Weight: Heaviness or lightness doesn't correlate with hardness. A heavy object can be soft, like lead, while a small, lightweight object can be hard, like a diamond.
In conclusion, the ability of a material to withstand scratching and compression effectively defines its hardness. Understanding this property helps in selecting materials for various applications based on their durability and resistance to wear.

Understanding Classification
Classification is the process of grouping objects based on shared characteristics or properties. This method helps in organizing and simplifying the vast array of items that we encounter in our daily lives.
Key Aspects of Classification:
- Definition: Classification involves sorting items into categories that share similarities, making them easier to study and understand.
- Purpose: The main goal is to create order among diverse objects, which helps in identifying, studying, and utilizing them effectively.
- Examples: Common examples of classification include:
- Living Organisms: In biology, organisms are classified into kingdoms, phyla, and species based on traits like structure and genetics.
- Library Systems: Books are classified by genre, author, or subject matter to facilitate easier access and organization.
- Household Items: Items in a kitchen can be classified as utensils, cookware, or appliances based on their function.
Benefits of Classification:
- Enhanced Understanding: By categorizing items, we can better understand their relationships and differences.
- Efficiency: Classification allows for quicker identification and retrieval of information, whether in studying or practical applications.
- Facilitates Communication: When items are classified, it becomes easier to discuss and share information about them using common terms.
In summary, classification is a vital process in organizing knowledge and objects, making it an essential concept in various fields of study and everyday life.

Understanding Lustrous Materials
Lustrous materials are those that have a shiny appearance and reflect light effectively. They are often metals or materials with a smooth surface. Let’s take a closer look at the options provided:
Options Explained
- Wood: Wood is a natural material that does not have a shiny surface. It typically has a matte finish and absorbs light rather than reflecting it.
- Iron: Iron is a metal known for its lustrous characteristics. When polished, it exhibits a shiny surface that reflects light, making it a classic example of a lustrous material.
- Rubber: Rubber is a synthetic material that usually has a dull appearance. It does not reflect light well and is not considered lustrous.
- Paper: Paper is another non-lustrous material. It tends to have a flat finish, absorbing light rather than reflecting it.
Conclusion
Among the options provided, iron stands out as the only lustrous material. Its metallic qualities enable it to shine when polished, making it a common choice for various applications where aesthetics and light reflection are important.
In summary, the correct answer is option 'B' (Iron) because it possesses the shiny, reflective properties characteristic of lustrous materials.

The SI unit of mass is the kilogram (kg), which is used for measuring larger masses.

Glass is transparent, allowing light to pass through, making it ideal for windows.

Understanding Transparent Materials
When it comes to light transmission, materials can be categorized into three main types: opaque, transparent, and translucent. Each type interacts with light differently.
Types of Materials
- Opaque: These materials do not allow any light to pass through. Examples include wood, metal, and thick fabrics. When light hits an opaque object, it is either absorbed or reflected, preventing visibility through the material.
- Transparent: Transparent materials allow light to pass through them clearly. This means that objects on the other side can be seen distinctly. Common examples include clear glass and clean water. The clarity of transparent materials makes them ideal for applications like windows and lenses.
- Translucent: Translucent materials allow some light to pass through, but not enough to see objects clearly. Examples include frosted glass and certain types of plastic. While light can filter through, the details on the other side remain blurred.
Key Characteristics of Transparent Materials
- Clarity: Transparent materials provide a clear view of objects behind them, making them essential for visibility.
- Light Transmission: They enable maximum light transmission, which is crucial for applications requiring illumination and visibility.
- Versatility: Used in various settings, from household windows to high-tech optical devices, transparent materials are vital in modern life.
In conclusion, the correct answer to the question is option 'B' – transparent materials are the ones that allow light to pass through them clearly, making them distinct from opaque and translucent materials.

Gas fills the space of its container and has mass, unlike solids and liquids which have a definite shape or volume.

Understanding Units of Volume
When measuring volume, it is essential to use the correct units to ensure clarity and accuracy. Let's analyze the options provided.
Option A: 500 Kg
- Explanation: "Kg" stands for kilograms, which is a unit of mass, not volume. Thus, this option is incorrect.
Option B: 2m³
- Explanation: "m³" (cubic meters) is indeed a unit of volume and is suitable for large measurements. However, in this context, we are looking for the most commonly used unit of volume, especially for liquids.
Option C: 1 Litre
- Explanation: "Litre" (or "liter") is also a unit of volume and is widely used for measuring liquids. However, it is typically abbreviated as "L" or "l." While this option is correct, it is not the best representation in the given choices.
Option D: 750 mL
- Explanation: "mL" stands for milliliters, which is a subunit of liters (1 L = 1000 mL). It is a common unit for measuring small volumes of liquids. This option is correct as it clearly defines a volume measurement that is frequently used in everyday situations.
Conclusion
In summary, while all options involve measurements, option D (750 mL) is the most appropriate answer in the context of volume units, especially in daily use for liquids. Always remember to choose the unit that best fits the context of the measurement!

Ancient Indian pottery was primarily made of clay, which was shaped and baked in kilns to create durable terracotta pots.

Paper is derived from trees, which are a natural resource, while plastic, glass, and metal are man-made materials.

Cotton is soft and can be easily compressed, unlike iron, wood, or glass.