Question 1: Why cannot a tumbler made of cloth be used for storing water?
Answer:
A tumbler made of cloth cannot be used for storing water because cloth allows water to pass through it. The water will leak out, and the cloth will become wet. Therefore, we cannot hold water in a cloth tumbler.
Question 2: Would it be a good idea to use paper-like materials for making cooking utensils?
Answer:
No, it would not be a good idea to use paper-like materials for making cooking utensils. Paper can catch fire easily and cannot handle the heat from cooking. Cooking utensils need to be made of materials that can withstand high temperatures without burning.
Question 3: Can a cricket ball be used to play tennis?
Answer:
No, a cricket ball cannot be used to play tennis. Cricket balls are hard and heavy, while tennis balls are lighter and softer. Using a cricket ball in tennis could be dangerous and would not work well for the game.
Question 4: Why are different materials used for making balls for various sports?
Answer:
Different sports require balls with specific properties like weight, bounce, and size. Materials are chosen to suit the game’s needs. For example, a football needs to be durable and kickable, so it is made of leather or synthetic material. A tennis ball needs to be light and bouncy, so it is made of rubber with a felt covering.
Question 5: Are all lustrous materials metals?
Answer:
No, not all lustrous (shiny) materials are metals. Some non-metal materials can also be shiny, like polished stones, certain plastics, or glass. While many metals are lustrous, shine alone does not mean a material is a metal.
Question 6: Is water transparent? Can it be made opaque?
Answer:
Yes, water is transparent because we can see through it clearly. Water can be made opaque (not see-through) by adding substances like milk or chalk powder, which make it cloudy and prevent us from seeing through it.
Question 7: Does everything you put in water disappear?
Answer:
No, not everything you put in water disappears. Some things like sugar and salt dissolve in water, but others like sand and oil do not dissolve and can still be seen.
Question 8: Do liquids like oil, vinegar, and honey dissolve in water?
Answer:
- Oil: Oil does not dissolve in water; it floats on top because it doesn’t mix with water.
- Vinegar: Vinegar dissolves in water because it mixes well and forms a solution.
- Honey: Honey dissolves in water if stirred, as it mixes with water to form a sweet solution.
Question 9: What about the gases present in water?
Answer:
Some gases can dissolve in water. For example, oxygen gas dissolves in water, which is important for fish and other aquatic animals to breathe underwater.
Question 10: Why was I not able to transfer water from the jug into an empty water bottle completely?
Answer:
Because the water bottle did not have enough space (volume) to hold all the water from the jug. The bottle was smaller than the amount of water you tried to pour, so some water remained in the jug.
Question 11: Are there any properties which can be shown by all materials? If yes, what are those?
Answer:
Yes, all materials have mass (they weigh something) and occupy space (they take up room). These are common properties of all materials.
Question 12: Is air matter?
Answer:
Yes, air is matter because it has mass and takes up space, even though we cannot see it.
Activity 6.1: Let us identify
Question: Make a list of objects you see around and also write the names of the materials they are made up of in Table 6.1.
Answer:
| I observe | Materials they are made up of |
|---|---|
| Chair | Wood |
| Water bottle | Plastic |
| Window | Glass |
| Notebook | Paper |
| Spoon | Metal |
| Shirt | Cloth |
Activity 6.2: Let us group
Question:
- Group the objects shown in Fig. 6.1 based on any common property, such as shape, colour, hardness, softness, shine, dullness or materials they are made up of.
- Which property did you use to group the objects in Activity 6.2?
- Did your friends group objects based on similar properties?
- What did you learn from this activity?
Answer:
- I grouped the objects based on their materials (wood, plastic, metal).
- I used the property of the material they are made of.
- Some of my friends grouped objects by color or by shape.
- I learned that objects can be grouped in many ways, and different people might choose different properties to group them.
Activity 6.3: Let us think
Question: Let us think what materials we can use to make a tumbler. Fill in the names of the materials in the spaces provided in Fig. 6.2.
Answer:
Materials used to make a tumbler:
- Glass
- Plastic
- Metal (like steel)
- Clay (for earthen pots)
Activity 6.4: Let us explore
Question:
- Take each ball and drop it from a fixed height.
- Note the height to which the ball bounces and record it in Table 6.2.
- Identify the ball that achieves the highest bounce.
Answer:
| Ball | Bounces (high, medium, or low) |
|---|---|
| Tennis ball | High |
| Cricket ball | Medium |
| Hand exercise ball | Low |
- The tennis ball achieved the highest bounce.
Activity 6.5: Let us observe
Question:
- Hold the objects given in Table 6.3 with your hands.
- Feel whether the objects are hard or soft. Find out the materials they are made up of.
- Enter your observations in Table 6.3.
Answer:
| Object | Hard/Soft | Material(s) |
|---|---|---|
| Brick | Hard | Baked clay |
| Water bottle | Hard | Plastic |
| Pillow | Soft | Cloth and cotton |
| Tumbler | Hard | Glass or plastic |
| Table | Hard | Wood |
| Sweater | Soft | Wool |
Activity 6.6: Let us classify
Question: Classify the following objects as transparent, translucent or opaque in Table 6.4.
Objects: Glass tumbler, Butter paper, Eraser, Frosted glass, Wooden board, Window glass.
Answer:
| Transparent | Translucent | Opaque |
|---|---|---|
| Glass tumbler | Butter paper | Eraser |
| Window glass | Frosted glass | Wooden board |
Activity 6.7: Let us explore
Question:
- Collect small amounts of sugar, salt, chalk powder, sand, and sawdust.
- Take five glass tumblers and fill them about two-third with water.
- Put a teaspoonful of each material in separate tumblers.
- Predict what will happen in each case.
- Stir well and observe.
- Write down your observations in Table 6.5.
Answer:
| Material | Prediction | Observation |
|---|---|---|
| Sugar | Will disappear in water | Disappears in water (soluble) |
| Salt | Will disappear in water | Disappears in water (soluble) |
| Chalk powder | Will not disappear in water | Does not disappear (insoluble) |
| Sand | Will not disappear in water | Does not disappear (insoluble) |
| Sawdust | Will not disappear in water | Does not disappear (insoluble) |
Activity 6.8: Let us measure
Question:
- Take three identical paper cups half-filled with:
- Cup A: Water
- Cup B: Sand
- Cup C: Pebbles
- Predict which one would be heavier and which one would be lighter.
- Weigh each cup and record the readings.
- Compare the data and infer which is heavier or lighter.
Answer:
- Prediction:
- Cup A (Water): Lightest
- Cup B (Sand): Heavier than water
- Cup C (Pebbles): Heaviest
- Observations:
- Cup A weighs 100 grams.
- Cup B weighs 150 grams.
- Cup C weighs 200 grams.
- Inference:
- Cup C is the heaviest, Cup A is the lightest.
Question 13: Are there any properties which can be shown by all materials? If yes, what are those?
Answer:
Yes, all materials have mass and take up space. These properties are common to all materials.
Exercise Questions
Question 1: Visit your kitchen and observe how your parents have organised various edibles. Can you suggest a better sorting method? Write it in your notebook.
Answer:
In my kitchen, items are placed randomly. I suggest grouping items like spices together, grains together, snacks together, and labeling containers. This will make it easier to find things.
Question 2: Unscramble the letters (Column I) and match with their properties (Column II).
Column I:
(i) T R E M A T
(ii) U L S B E L O
(iii) T N E R P A S N A R T
(iv) E R U S T L
Column II:
(a) Objects can be seen clearly through it
(b) Occupies space and has mass
(c) Shiny surface
(d) Mixes completely in water
Answer:
Unscrambled words:
(i) MATTER
(ii) SOLUBLE
(iii) TRANSPARENT
(iv) LUSTRE
Matching:
(i) MATTER – (b) Occupies space and has mass
(ii) SOLUBLE – (d) Mixes completely in water
(iii) TRANSPARENT – (a) Objects can be seen clearly through it
(iv) LUSTRE – (c) Shiny surface
Question 3: The containers which are used to store materials in shops and at home are usually transparent. Give your reasons for this.
Answer:
Transparent containers allow us to see what is inside without opening them. This helps in quickly identifying the contents and knowing how much is left.
Question 4: 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. [ ]
Answer:
(i) False. Correct statement: Wood is opaque while glass is transparent.
(ii) True.
(iii) True.
(iv) False. Correct statement: An apple is matter because it occupies space and has mass.
Question 5: 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.
Answer:
(i) Hardness: Iron, cement, and stone chairs are very hard.
(ii) Lightweight: Plastic and bamboo chairs are lightweight.
(iii) Not cold in winters: Wooden and plastic chairs do not feel very cold.
(iv) Easy to clean: Plastic and metal chairs can be cleaned easily and look new.
Question 6: 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?
Answer:
(i) Food waste: A plastic bin with a lid; properties needed are durability and easy to clean.
(ii) Broken glass: A strong cardboard box or plastic container; properties needed are strength and safety.
(iii) Wastepaper: A lightweight basket or bin; properties needed are lightness and ease of use.
Question 7: 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
Answer:
Option (i): Air is transparent, and the wooden door is opaque.
Question 8: 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.
Answer:
Material X is hard because it is rigid and does not change shape easily. It dissolves in water, so it could be salt or sugar.
Material Y is soft because it changes shape easily and does not dissolve in water. It could be clay or rubber.
Question 9:
(i) Who am I? Identify me on the basis of the given properties.
(a) I have lustre.
Answer: A metal like gold or silver.
(b) I can be easily compressed.
Answer: A sponge or cotton.
(c) I am hard and soluble in water.
Answer: Salt.
(d) You cannot see clearly through me.
Answer: A translucent material like frosted glass.
(e) I have mass and volume but you cannot see me.
Answer: Air.
(ii) Make your own ‘Who am I?’
Question: I am transparent and used to make bottles. Who am I?
Answer: Glass or clear plastic.
Question 10: 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.
Answer:
Soluble pairs:
- Water and vinegar: Vinegar dissolves in water.
- Water and glucose: Glucose dissolves in water.
Insoluble pairs:
- Water and mustard oil: Mustard oil does not dissolve in water.
- Water and wheat flour: Wheat flour does not dissolve; it forms a paste.
Additional Activities:
Gather information on different materials which can be recycled.
Answer:
Materials that can be recycled include paper, glass, metals like aluminum and steel, and certain plastics. Recycling helps reduce waste and saves resources.
Conduct a survey with recyclers near you and find out what properties of materials they check before buying objects from households. Which materials do they not buy and why?
Answer:
Recyclers look for materials that are recyclable and in demand. They check for materials like metals, certain plastics, and paper. They might not buy materials that are not recyclable or are contaminated. They avoid materials like certain types of plastic that cannot be recycled easily.
Collect 20–30 objects from your household and classify them based on the properties of the materials they are made up of. Were you able to put them in separate groups? What relationship do you see between the properties of the materials and the use of the objects?
Answer:
Yes, I grouped objects into categories like metals (spoons, keys), plastics (toys, bottles), glass (jars, cups), and fabrics (clothes, towels). The properties of materials relate to their use. For example, metals are strong and used for tools, plastics are lightweight and used for containers, glass is transparent and used for bottles.
Create and decorate a useful object of your choice using discarded materials and bring it to the class. Discuss with your friends what they have made and the materials they have used. Additionally, provide constructive feedback on areas for improvement, considering functionality and any other points.
Answer:
I made a pencil holder using an old tin can and decorated it with colored paper. My friends appreciated it and suggested adding a base to prevent scratches on the table.