📘 Chapter 6: Materials Around Us
📝 “Let us enhance our learning” (Exercises)
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:
- Observation of current kitchen organisation: Edibles in the kitchen are usually grouped into spices, grains, pulses, and cooking oils.
- Suggested better sorting/classification method:
- Transparent and labelled containers: Store all pulses, grains, and spices in transparent glass or plastic jars with clear labels so that items can be identified without opening the lids.
- Frequency of use: Place daily needed items (salt, sugar, tea, turmeric) on lower, easily accessible shelves, and occasionally used items on higher shelves.
- Segregation by state/type: Keep dry items (flour, pulses) away from liquid items (oils, sauce bottles) to prevent damage from accidental spills.
Question 2. Unscramble the letters (Column I) and match with their properties (Column II).
Answer (Unscrambled and Matched):
| Column I (Unscrambled Word) | Column II (Property) |
|---|---|
| (i) MATTER (TREMAT) | (b) Occupies space and has mass |
| (ii) SOLUBLE (ULSBELO) | (d) Mixes completely in water |
| (iii) TRANSPARENT (TNERPASNART) | (a) Objects can be seen clearly through it |
| (iv) LUSTRE (ERUSTL) | (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:
- Easy Identification: Transparent containers (made of glass or clear plastic) allow us to see the contents inside clearly without opening the lid.
- Saves Time and Effort: Shopkeepers and homemakers can quickly locate the required item (spices, sweets, pulses) without searching through multiple jars.
- Quantity Monitoring: It helps to easily check the remaining quantity of stored items so that new purchases can be planned in advance.
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.
Answer: [ F ]
Correct Statement: Wood is opaque while glass is transparent. - (ii) Aluminium foil has lustre while an eraser does not.
Answer: [ T ] - (iii) Sugar dissolves in water whereas sawdust does not.
Answer: [ T ] - (iv) An apple is a matter because it occupies no space and has mass.
Answer: [ F ]
Correct Statement: An apple is matter because it occupies space (has volume) 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: Plastic (and Wood / Bamboo) fulfills most of these desirable properties.
Explanation:
- Plastic: It is sufficiently hard to support weight without bending, lightweight to move easily, does not feel very cold in winter (unlike iron or stone), and can be easily cleaned with water to look new.
- Wood / Bamboo: Hard, lightweight, non-conductive (feels comfortable in winter), though wood requires periodic polishing.
- (Note: Iron and Stone chairs are heavy and feel very cold during winter, while Cement chairs are fixed and heavy).
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:
| Type of Waste | Chosen Material for Container | Essential Properties Considered |
|---|---|---|
| (i) Food waste (Wet waste) | Thick Plastic or Stainless steel | Waterproof (leak-proof), non-corrosive, easy to wash, and non-reactive. |
| (ii) Broken glass (Sharp waste) | Heavy-duty Metal (Iron/Tin) or Rigid Plastic | Hard, tough, puncture-resistant, and opaque to safely hold sharp edges without breaking. |
| (iii) Wastepaper (Dry waste) | Cardboard box, Plastic bin, or Bamboo basket | Lightweight, dry, cost-effective, and easy to carry. |
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: (i) transparent, opaque
- Reason: Air allows light to pass through completely, making it transparent; a wooden door blocks light completely, making it 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:
- Identification: Material X is Hard and Soluble in water.
- Possible Example: Rock salt / Common salt crystal or Sugar crystal.
- Material Y:
- Identification: Material Y is Soft and Insoluble in water.
- Possible Example: Cotton / Sponge / Wax / Clay.
- Justification: Materials that cannot be easily compressed or scratched are hard (Material X), while materials that compress easily are soft (Material Y). Materials that completely disappear in water are soluble (Material X), while those that do not dissolve are insoluble (Material Y).
Question 9. (i) Who am I? Identify me on the basis of the given properties:
- (a) I have lustre.
Answer: Metal (such as Gold, Copper, Aluminium, or Iron). - (b) I can be easily compressed.
Answer: Soft material (such as Sponge, Cotton, or Rubber). - (c) I am hard and soluble in water.
Answer: Salt or Sugar. - (d) You cannot see clearly through me.
Answer: Translucent material (such as Butter paper, Frosted glass, or Tissue paper). - (e) I have mass and volume but you cannot see me.
Answer: Air (or Oxygen/Gases).
(ii) Make your own 'Who am I?' riddles:
- Riddle 1: "I am opaque, heavy, hard, and used for building walls. Who am I?" ➔ Brick / Stone.
- Riddle 2: "I am transparent, liquid, essential for life, and can dissolve many substances. Who am I?" ➔ Water.
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:
- Two Soluble Pairs (One material dissolves completely in the other):
- Vinegar + Water (or Honey + Water)
- Glucose + Water
- Two Insoluble Pairs (One material does not dissolve/mix in the other):
- Mustard oil + Water (Mustard oil forms a separate layer on water)
- Wheat flour + Water (or Wheat flour + Mustard oil)
🔬 “Learning further” (Projects & Field Activities)
Recycling and Recyclers Survey:
- Recyclable Materials: Paper, cardboard, glass bottles, metals (iron/aluminium), and rigid plastics.
- Properties Recyclers Check: Scrap buyers check the material type (metal, plastic, paper, glass) regardless of whether the item is broken or whole. They do not buy wet paper, thermocol, or hazardous chemical containers as they cannot be recycled safely.
Classification of Household Objects:
- Activity: Collect 20–30 household items (spoon, mirror, notebook, eraser, plastic bottle, coin, glass, etc.) and group them based on lustre, hardness, solubility, and transparency.
- Relationship: An object's properties dictate its practical use. For example, glass is chosen for window panes because it is transparent, while metals are chosen for utensils because they are hard and durable.
"Best out of Waste" Activity:
- Project Idea: Cut a discarded plastic bottle, decorate its exterior, and turn it into a useful Pen-Stand or a small Plant Pot for the classroom.
Note: If there are any errors in the provided answers or details, please contact us at trhelpmail@gmail.com.