Q1: Answer in short.
1. What do you mean by classification?
2. What is the need for classification?
3. Why is mercury used in making thermometers?
4. On what basis are the various objects grouped?
5. Why do we need the grouping of objects?
6. How does the grouping of objects help the shopkeeper?
7. Name the various materials from which following things can be made:
Shoes, chair, coins, utensils, clothes.
8. Name any four materials that can be used to make school bags.
9. List any three solutions that are used in your home.
10. Why is water important for our body?
11. List five each opaque and transparent materials.
12. List five objects that are made from transparent materials.
13. List five liquids that are transparent.
14. List five objects that are made from an opaque materials.
15. Why is water called universal solvent?
16. List three liquids which are miscible in water.
17. List three liquids which are immiscible in water.
18. State conditions when pure water can lose transparency.
19. List the following substances as soluble and insoluble in water.
Sand, salt, sugar, paint, chilli powder, desi ghee, blotting paper.
20. Show that sugar, common salt and washing soda are soluble while
3
Answers
Answer:
Question 1.
What do you mean by classification?
Answer:
Classification is the grouping or sorting together of things possessing similar or dissimilar characteristics or properties.
Question 2.
What is the need for classification?
Answer:
Classification is essential for:
identification of objects.
sorting of objects.
locating things.
understanding similarities and dissimilarities among objects.
making the study of objects easy and more meaningful.
Question 3.
Why is mercury used in making thermometers?
Answer:
Mercury is liquid at room temperature.
It is a good conductor of heat.
Mercury has lustre, so, it is easy to read the temperature shown by the level of mercury.
Question 4.
On what basis are the various objects grouped?
Answer:
The grouping of various objects can be done on the basis of following characters:
size
shape
colour
hardness
solubility in water
attraction towards magnet
conduction of heat
transparency, etc.
Question 5.
Why do we need the grouping of objects?
Answer:
Grouping the objects helps us to arrange them in a systematic manner. The objects when grouped are easy to handle. When grouped, it is easy to know the properties of an object clearly. Grouping also makes easy to compare two objects.
Question 6.
How does the grouping of objects help the shopkeeper?
Answer:
The grouping of objects in proper way makes it easier to work. When we go to purchase some things, the shopkeeper locates it easily, because there are separate shelves to put various items and similar things are kept at one place. If he randomly places all of these, he would never be able to find them so quickly and easily.
Question 7.
Name the various materials from which following things can be made:
Shoes, chair, coins, utensils, clothes.
Answer:
Shoes: Leather, rubber, plastic, canvas
Chair: Wood, metal, plastic, concrete
Coins: Copper, silver, gold
Utensils: Iron, copper, aluminium
Clothes: Cotton, wool, silk, rayon, nylon.
Question 8.
Name any four materials that can be used to make school bags.
Answer:
Cloth (of cotton, jute, nylon, etc.), plastic, metal or alloy.
Question 9.
List any three solutions that are used in your home.
Answer:
Salt solution, sugar solution, cold drinks, lime juice, etc.
Question 10.
Why is water important for our body?
Answer:
Water can dissolve a large number of substances, so it is needed by the body. It is also major part of our body cells.
Activity 2
Table 4.2 lists some common materials. You can also add more materials in Column 1 that are known to you. Now, try and think of everyday objects you know, that are made mainly of these materials, and list them in Column 2.
Table 4.2: Different types of objects that are made from the same material
Material Objects made of these materials
Wood Chair, table, plough, bullock cart and its wheels, …
Papier Books, notebooks, newspapers, toys, calendars, …
Leather Shoes, belt, purse, bag, jacket
Plastics Mug, bottle, bucket, toy
Cotton Clothes, curtains, bed sheets, sari
Properties of materials
Question 1.
List five each opaque and transparent materials.
Answer:
Opaque materials:
Wood
Iron
Cardboard
Brick
Gold.
Transparent materials:
Water
Glass
Air
Cellophine plastic, and
Fibre glass.
Question 2.
List five objects that are made from transparent materials.
Answer:
Beaker,
Test tube,
Conical flask,
Glass jug, and
Glass doors.
Question 3.
List five liquids that are transparent.
Answer:
Water
Hydrochloric acid
Alcohol
Acetone, and
Petrol.
Question 4
List five objects that are made from an opaque material.
Answer:
Books
Blackboard
Cardboard
Wall, and
Wooden furniture.
Question 5.
Why is water called universal solvent?
Answer:
The property of water to dissolve large number of materials makes it a universal solvent.
Question 6.
List three liquids which are miscible in water.
Answer:
Answer:
HEY MATE HERE'S YOUR ANSWER
Explaination:
1 Answer
Classification is the grouping or sorting together of things possessing similar or dissimilar characteristics or properties
2 Answer
Classification is essential for:
-identification of objects.
-sorting of objects.
-locating things.
-understanding similarities and dissimilarities among objects.
-making the study of objects easy and more meaningful
3 Answer
-Mercury is liquid at room temperature.
-It is a good conductor of heat.
-Mercury has lustre, so, it is easy to read the temperature shown by the level of mercury.
4 Answer
The grouping of various objects can be done on the basis of following characters:
-size
-shape
-colour
-hardness
-solubility in water
-attraction towards magnet
-conduction of heat
-transparency, etc.
5 Answer
Grouping the objects helps us to arrange them in a systematic manner. The objects when grouped are easy to handle. When grouped, it is easy to know the properties of an object clearly. Grouping also makes easy to compare two objects
6 Answer
The grouping of objects in proper way makes it easier to work. When we go to purchase some things, the shopkeeper locates it easily, because there are separate shelves to put various items and similar things are kept at one place. If he randomly places all of these, he would never be able to find them so quickly and easily
7 Answer
-Shoes: Leather, rubber, plastic, canvas
-Chair: Wood, metal, plastic, concrete
-Coins: Copper, silver, gold
-Utensils: Iron, copper, aluminium
-Clothes: Cotton, wool, silk, rayon, nylon
8 Answer
Cloth (of cotton, jute, nylon, etc.), plastic, metal or alloy.
9 Answer
Salt solution, sugar solution, cold drinks, lime juice, etc.
10 Answer
Water can dissolve a large number of substances, so it is needed by the body. It is also major part of our body cells.
11 Answer
Opaque materials:
-Wood
-Iron
-Cardboard
-Brick
-Gold.
Transparent materials:
-Water
-Glass
-Air
-Cellophine plastic, and
-Fibre glass.
12 Answer
-Beaker,
-Test tube,
-Conical flask,
-Glass jug, and
-Glass doors.
13 Answer
-Water
-Hydrochloric acid
-Alcohol
-Acetone, and
-Petrol.
14 Answer
-Books
-Blackboard
-Cardboard
-Wall, and
-Wooden furniture.
15 Answer
The property of water to dissolve large number of materials makes it a universal solvent.
16 Answer
-Milk
-glycerine, and
-soft drinks
17 Answer
-Edible oil
-kerosene oil, and
-petrol.
18 Answer
Water on cooling, freezes to form ice which is not transparent.
19 Answer
Water soluble substances: Salt, sugar.
Water insoluble substances: Sand, paint, chilli powder, desi ghee, blotting paper.
20 Answer
Take six test tubes, fill each of them about half with water. Keep each of them in a test tube stand. Add a pinch of each of six substances in separate test tubes. Shake well and allow to stand for few minutes. Common salt, sugar and washing soda dissolve while iodine, chalk powder and sand do not dissolve.
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