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Tamil Nadu Board of Secondary EducationTamil Nadu Primary School Class 4
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Various uses of changes in physical state

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Various Uses of Changes in Physical State:

Use Case Material Used Change in State Process Benefits of This Change
Making Candles Paraffin wax Solid to liquid Paraffin wax is heated until it melts. Once it is in liquid form, it is poured into moulds. As it cools, it solidifies into the shape of the candle. Enables the creation of versatile candle designs for lighting and decoration.
Using Dry Ice in Food Preservation and Preparation Solid carbon dioxide (dry ice) Solid to gas (sublimation) Dry ice is used to keep ice cream frozen during transport because it is much colder than regular ice. It can also be used to make ice cream by quickly freezing the cream mixture. Maintains the cold temperature of ice cream without moisture, preventing mess and contamination.
Liquid Nitrogen in Animal Husbandry Liquid nitrogen Liquid to gas Liquid nitrogen is extremely cold and is used to freeze and store biological material like sperm and eggs in animal breeding programs. Preserves biological materials effectively without cellular damage, crucial for successful animal breeding.
Making Glass from Sand Sand (primarily composed of silica) Solid to liquid Sand is heated to very high temperatures until it melts into a liquid. This liquid is then shaped and cooled to form glass. Allows for the production of a wide range of glass products, from windows to bottles.
Melting Metals to Make Ornaments Gold, silver Solid to liquid Metals like gold and silver are melted so they can be poured into moulds to create jewellery and ornaments. Facilitates intricate jewellery designs, enhancing aesthetic appeal and value.
Melting Iron to Make Tools Iron Solid to liquid Iron is melted in a furnace and then poured into moulds to make various tools and machinery parts. Produces strong and durable tools essential for construction and manufacturing industries.

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Related QuestionsVIEW ALL [67]

Match the objects given in Column I with the materials given in Column II.

COLUMN I COLUMN II
(a) Surgical
instruments		 (i) Plastic
(b) Newspaper (ii) Animal product
(c) Electrical switches (iii) Steel
(d) Wool (iv) Plant
product

A notebook has lustre while an eraser does not.

Sugar, salt, mustard oil, sand, sawdust, honey, chalk powder, petals of flower, soil, copper sulphate crystals, glucose, wheat flour are some substances given to Paheli. She wants to know whether these substances are soluble in water or not. Help her in identifying soluble and insoluble substances in water.

While doing an activity in class, the teacher asked Paheli to .handover a translucent material. Which among the following materials will Paheli pick and give her teacher?

Complete the crossword given in figure with the help of the clues.

Across

1. Which is generally hard, ductile, malleable and sonorous.

2. A metal is called so, it can be drawn into wires.

3. Metal bells are used because of this property.

Down

4. A metal generally used for making jewellery.

5. A metal which -is liquid at room temperature.

6. A metal which reacts with acid as f well as base to form hydrogen gas.

7. Substances used to enhance the growth of plants.

8. Property by virtue of which metals can be beaten into thin sheets.

lt was Paheli’s birthday. Her grandmother gave her two gifts made of metals, one old dull silver spoon and a pair of lustrous gold earrings. She was surprised to see the difference in the appearance of the two metals. Can you explain the reason for this difference?

Very Short Answer Type Question:

Name two objects which are made from opaque materials.

Very Short Answer Type Question:

Why do we need to group materials? Give one reason.

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