Materials Around UsClass 6 Science NCERT Solutions
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Q1Let us enhance our learning
Visit your kitchen and observe how your parents have organised various edibles. Can you suggest a better sorting method? Write it in your notebook.
Solution
In a kitchen, edibles are often organised based on various properties like type (spices, grains, pulses, oils), frequency of use, shelf life, or storage requirements (refrigerated, dry storage). While parents might have their own efficient system, a better sorting method could focus on:
- Grouping by type: All spices together, all grains together, all pulses together. This helps in quickly locating ingredients.
- Grouping by usage: Items used daily at the front, items used occasionally at the back.
- Grouping by storage conditions: All dry goods in airtight containers, all refrigerated items in one section.
- Labelling: Clear labels on containers for easy identification, especially for similar-looking items like different flours or spices.
This systematic approach can improve efficiency, reduce clutter, and prevent spoilage.
Q2Let us enhance our learning
Unscramble the letters (Column I) and match with their properties (Column II).
\begin{tabular}{|l|l|}
\hline Column I & Column II
\hline (i) TREMAT & (a) Objects can be seen clearly through it
\hline (ii) ULS B E L O & (b) Occupies space and has mass
\hline (iii) TNERPASNART & (c) Shiny surface
\hline (iv) E R U S T L & (d) Mixes completely in water
\hline
\end{tabular}
Solution
Here is the unscrambled and matched list:
- (i) TREMAT unscrambles to MATTER (b) Occupies space and has mass
- (ii) ULS B E L O unscrambles to SOLUBLE (d) Mixes completely in water
- (iii) TNERPASNART unscrambles to TRANSPARENT (a) Objects can be seen clearly through it
- (iv) E R U S T L unscrambles to LUSTRE (c) Shiny surface
Q3Let us enhance our learning
The containers which are used to store materials in shops and at home are usually transparent. Give your reasons for this.
Solution
Containers used to store materials in shops and at home are usually transparent because:
- Visibility: Transparent containers allow us to see the contents inside without opening them. This helps in quickly identifying what is stored and how much is left.
- Convenience: In shops, customers can easily see the product, its quality, and quantity, which aids in their purchasing decision. At home, it helps in efficient organisation and prevents confusion.
- Aesthetics: For certain items, transparent containers can also be aesthetically pleasing, showcasing the product clearly.
Q4Let us enhance our learning
State whether the statements given below are True [T] or False [F]. Correct the False statement(s).
(i)
Wood is translucent while glass is opaque.
(ii)
Aluminium foil has lustre while an eraser does not.
(iii)
Sugar dissolves in water whereas sawdust does not.
(iv)
An apple is a matter because it occupies no space and has mass.
Solution
(i)
False [F]. Wood is opaque while glass is transparent.
(ii)
True [T].
(iii)
True [T].
(iv)
False [F]. An apple is a matter because it occupies space and has mass.
Q5Let us enhance our learning
We see chairs made up of various materials, such as wood, iron, plastic, bamboo, cement and stones. Following are some desirable properties of materials which can be used to make chairs. Which materials used to make chairs fulfil these properties the most?
(i)
Hardness (does not bend or shake on sitting even after long use).
(ii)
Lightweight (easy to lift or to take from one place to another).
(iii)
Does not feel very cold when sitting during winters.
(iv)
Can be cleaned regularly and made to look new even after long use.
Solution
Here are the materials that best fulfil the desirable properties for making chairs:
(i)
Hardness (does not bend or shake on sitting even after long use): Iron, Cement, Stones, Wood (hardwoods), high-quality Plastic.
(ii)
Lightweight (easy to lift or to take from one place to another): Plastic, Bamboo, Wood.
(iii)
Does not feel very cold when sitting during winters: Wood, Plastic, Bamboo.
(iv)
Can be cleaned regularly and made to look new even after long use: Plastic, Iron (if properly coated/treated), Polished Cement/Stone.
Q6Let us enhance our learning
You need to have containers for collection of: (i) food waste, (ii) broken glass and (iii) wastepaper. Which materials will you choose for containers of these types of waste? What properties of materials do you need to think of?
Solution
When choosing materials for waste containers, we need to consider the properties that make them suitable for holding specific types of waste safely, hygienically, and efficiently.
(i)
Food waste:
* Material choice: Plastic or metal (e.g., stainless steel).
* Properties to think of: The material should be non-absorbent to prevent liquids from leaking, easy to clean to maintain hygiene, odor-resistant, and durable to withstand daily use. It should also be opaque to hide the contents.
(ii)
Broken glass:
* Material choice: Hard plastic or metal (e.g., thick plastic bin, metal bucket).
* Properties to think of: The material must be hard and sturdy to prevent sharp glass pieces from piercing through or breaking the container. It should be opaque for safety reasons, so people do not accidentally come into contact with the broken glass.
(iii)
Wastepaper:
* Material choice: Cardboard, plastic, or metal.
* Properties to think of: The material should be lightweight for easy movement, durable enough to hold paper, and ideally recyclable. It can be opaque or translucent as visibility of contents is not a major concern here.
Q7Let us enhance our learning
Air is all around us but does not hinder us from seeing each other. Whereas, if a wooden door comes in between, we cannot see each other. It is because air is ____ and the wooden door is ____ Choose the most appropriate option:
(i)
transparent, opaque
(ii)
translucent, transparent
(iii)
opaque, translucent
(iv)
transparent, translucent
Solution
The most appropriate option is (i) transparent, opaque.
Air is transparent, meaning things can be seen clearly through it. A wooden door is opaque, meaning things cannot be seen through it at all.
Q8Let us enhance our learning
Imagine you have two mysterious materials, X and Y . When you try to press material X, it feels rigid and does not change its shape easily. On the other hand, material Y easily changes its shape when you press it. Now, when you mix both materials in water, only material X dissolves completely, while material Y remains unchanged. What can materials X and Y be? Can you identify whether material X is hard or soft? What about material Y? Justify your answer.
Solution
Based on the given properties:
-
Material X:
- Property: Feels rigid and does not change its shape easily when pressed.
- Conclusion about hardness/softness: Material X is hard.
- Property: Dissolves completely in water.
- Conclusion about solubility: Material X is soluble in water.
- Possible examples: Sugar, salt, or any other crystalline substance that is hard and water-soluble.
-
Material Y:
- Property: Easily changes its shape when pressed.
- Conclusion about hardness/softness: Material Y is soft.
- Property: Remains unchanged when mixed in water.
- Conclusion about solubility: Material Y is insoluble in water.
- Possible examples: Chalk powder, sawdust, clay, or a soft piece of rubber that does not dissolve in water.
Justification: The definitions of hard and soft materials in the chapter state that materials difficult to compress or scratch are hard, and those easily compressed or scratched are soft. Similarly, materials that disappear completely in water are soluble, and those that do not are insoluble.
Q9Let us enhance our learning
(i) Who am I? Identify me on the basis of the given properties.
(a)
I have lustre.
(b)
I can be easily compressed.
(c)
I am hard and soluble in water.
(d)
You cannot see clearly through me.
(e) I have mass and volume but you cannot see me.
Solution
(i) Here are the identifications based on the given properties:
(a) I have lustre.
* Answer: Metal (e.g., gold, iron, copper, aluminium)
(b) I can be easily compressed.
* Answer: Soft material (e.g., sponge, rubber, cotton)
(c) I am hard and soluble in water.
* Answer: Sugar, Salt
(d) You cannot see clearly through me.
* Answer: Translucent material (e.g., frosted glass, butter paper)
(e) I have mass and volume but you cannot see me.
* Answer: Air (or any other invisible gas)
Q10Let us enhance our learning
You are provided with the following materials-vinegar, honey, mustard oil, water, glucose and wheat flour. Make any two pairs of materials where one material is soluble in the other. Now, make two pairs of materials where one material remains insoluble in the other material.
Solution
Here are the pairs of materials based on solubility:
Pairs where one material is soluble in the other:
- Water and Vinegar: Vinegar (acetic acid mixed with water) is completely miscible and soluble in water.
- Water and Glucose: Glucose powder dissolves completely in water to form a solution.
Pairs where one material remains insoluble in the other material:
- Water and Mustard oil: Mustard oil is immiscible in water; it forms a separate layer when mixed.
- Water and Wheat flour: Wheat flour does not dissolve in water; it forms a suspension and settles down or forms a paste.
- Vinegar and Mustard oil: Vinegar and mustard oil are also immiscible and will form separate layers.
Q1Let us play
Find the companion. Link the following words by putting arrows between words that have a connection. Iron Transparent Copper Solid Bottle Plastic Lustrous Wood Opaque Glass
Solution
Here are the connections between the words:
- Iron Lustrous
- Iron Solid
- Iron Opaque
- Copper Lustrous
- Copper Solid
- Copper Opaque
- Plastic Bottle
- Plastic Opaque (can also be translucent/transparent, but commonly opaque in bottles)
- Wood Solid
- Wood Opaque
- Glass Transparent
- Glass Bottle
- Bottle Plastic
- Bottle Glass
- Solid Iron
- Solid Copper
- Solid Wood
- Lustrous Iron
- Lustrous Copper
- Transparent Glass
- Opaque Iron
- Opaque Copper
- Opaque Wood
- Opaque Plastic