Class 6 Science Notes for Sorting Material Into Group

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CLASS 6
SCIENCE

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Sorting Material into Groups
• Objects around us are made up of a large variety of materials.
• A given material could be used to make a large number of objects. It is also possible that
an object could be made of a single material or of many different types of materials.
Classification
Materials can be classified based on several properties:

 Transparency
 Hardness
 Soluble and Insoluble
 Float and Sink
• Different types of materials have different properties.
• Some materials are shiny in appearance while others are not. Some are rough, some
smooth. Similarly, some materials are hard, whereas some others are soft.
• Some materials are soluble in water whereas some others are insoluble.
• Some materials such as glass, are transparent and some others such as wood and metals
are opaque. Some materials are translucent.
• Materials are grouped together on the basis of similarities and differences in their
properties.
• Things are grouped together for convenience and to study their properties.
• Materials are classified based on their properties like: appearance, hardness, solubility,
float/ sink, transparency, conduction of heat, states of matter, conduction of electricity,
attraction towards magnets, combustibility.
• Advantages of classification:
(a) Helps in identification of objects.
(b) Helps in sorting of objects.
(c) Helps in locating things.
(d) Makes study of different objects easy and more meaningful rather than studying each

other separately.
(e) Helps to understanding similarities and dissimilarities among objects.

Polishing

 Metal polishing acts as a protective shield to metal surfaces because it stops oxidation.
 It is a method of improving the durability and texture of metal surfaces as they are much
less likely to wear or corrode.
Lustre

 Some like diamond and gold are shiny and is termed as lustrous materials.
Non- Lustre
 Some other materials like graphite and wood do not appear shiny and are generally
known as non-lustrous materials
Soft Substance
 Materials that can be compressed or deformed easily are referred to as soft substances.
Hard Substance
 Materials that are difficult to bend or compress and are termed as hard substances
Soluble Substance
 Some substances completely disappear or dissolve in water. These substances are soluble
in water.

Non-soluble Substance
 Some substances do not mix with water and do not disappear even after we stir for a long
time. These substances are insoluble in water.
Buoyancy
 The upward force applied by the fluid on the object or the body when an object is put in
or submerged in the fluid is termed as Buoyancy.

Density
Density is defined as mass per volume. You can think of it as the amounts of particles of a
substance are packed into a certain amount of space.
Transparent Object
 An object, which allows visible light to pass through it is called a transparent object. We
can clearly see through a transparent object. E.g.:- glass, fish tank.

Translucent Object

 An object, which allows partial passage to light is called a translucent object. E.g.:-plastic
bottle, paper cup.

Some Important Questions-
1. Why do we need to group materials? Give one reason.
Ans: We often group materials for our convenience. It helps to describe their properties.
2. Suggest two bases on which we can group objects.
Ans:
(i) Material used in making the object, e.g. wood or metal/plastic.
(ii) Material of the object is soft or hard, or substance is soluble or insoluble in water.
3. Is a substance which can be compressed soft or hard?
Ans: Soft.
4. Select a lustrous material out of the following substances:
Ans: Aluminium.
5. Which material is generally used for making pens? Wood, aluminium, plastic, cotton
Ans: Plastic or metal.
6. Is oil soluble in water?
Ans: Oil does not dissolve in water so it is insoluble in water but floats on the surface of water.
7. Name two objects which are made from opaque materials.
Ans: Wooden doors, blackboard/steel plate.
8. What is common between salt and sand?
Ans: Both have mass and are in solid state.
9. List three liquids which are transparent.
Ans. Water, alcohol and Acetone/Benzene.
10. Write two substances which are made from leather.
Ans: Belt and shoes.
11. Name some substances which are made from plastics.
Ans: Toys, plates, cups, buckets, baskets.
12. Which is harder, sponge or iron?
Ans: Iron is harder than sponge.
13. Write two gases which are soluble in water.
Ans: Oxygen, Carbon dioxide.
14. Name two gases which are insoluble in water.
Ans: Hydrogen and Nitrogen.

SHORT ANSWER TYPE QUESTIONS
1. Write any four properties of materials.
Ans: (a) Appearance (b) Hardness (c) Solubility (d) Float or sink in water (e) Transparency
2. Why is a tumbler not made with a piece of cloth?
Ans: We use tumblers made of glass, plastic and metal to keep a liquid. These substances can
hold a liquid.
A tumbler made of cloth cannot hold a liquid because:
(i) Cloth piece is not hard enough to hold liquids and
(ii) Cloth piece has very minute pores through which the‘liquid oozes out.
3. What are the similarities between iron, copper and aluminium?
Ans: (a) They all have lustre (b) They are all metals (c) They are hard.
4. Mention some materials which are made up of paper.
Ans: Books, notebooks, newspapers, toys, calendars, etc.
5. Why is water important for our body?
Ans: Water can dissolve a large number of substances, so it is needed by the body. It is also
major part of our body cells.
6. What is the basis for sorting materials?
Ans: Materials are grouped on the basis of similarities or dissimilarities in their properties.
7. What is the reason for grouping materials?
Ans: Materials are grouped for our convenience to study their properties and also observe any
patterns in these properties.
8. Metals have lustre (shine). Give reason why some metal articles become dull and loose their
shine.
Ans: Metals when exposed to air react with moisture and gases present in it, thereby forming a
dull layer of some other compound on it.
9. Kerosene, coconut oil, mustard oil do not dissolve in water, even on shaking. They separate
after sometime forming two different layer. Explain why.
Ans: The molecules of water do not intermingle (mix) with the molecules of oil. The space
between the molecules of water is not taken by oil, so they are immiscible in water.
10. Name a non-metal that has lustre.
Ans: Iodine.
11. Metals generally occur in solid state and are hard. Name a metal that exists in liquid state and
a metal that is soft and can be cut with knife.
Ans: Mercury is a metal that exists in liquid state. Sodium and Potassium are soft metals and can
be cut with knife.
12. Name the naturally occurring hardest substance known.
Ans: Diamond, it is made up of carbon (non-metal).
13. Why is water called a universal solvent?
Ans: Water dissolves a large number of substances in it. So it is called universal solvent.

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