Extra 30 short questions and answers from the CBSE Class 6 Science chapter:4 "Sorting Materials into Groups."
1. Why do we need to group materials?
✅ Answer:
Grouping helps in identifying and understanding materials better.
It makes storage, selection, and usage easier.
It helps in studying properties like hardness, solubility, and conductivity.
2. What is meant by transparency of materials?
✅ Answer:
Transparency is the ability of a material to allow light to pass through.
Transparent materials (e.g., glass) allow full light to pass.
Translucent materials (e.g., butter paper) allow partial light to pass.
Opaque materials (e.g., wood) do not allow light to pass.
3. What are the different types of materials based on their appearance?
✅ Answer:
Materials can be
shiny
(e.g., metals like gold and silver) or
dull
(e.g., wood and plastic).
Some materials can lose their shine over time due to oxidation.
The appearance of a material helps in identifying its nature and usage.
4. What is solubility? Give examples of soluble and insoluble substances.
✅ Answer:
Solubility
refers to the ability of a substance to dissolve in a liquid.
Soluble substances
: Sugar, salt (dissolve in water).
Insoluble substances
: Sand, chalk powder (do not dissolve in water).
5. What is meant by hardness and softness of materials?
✅ Answer:
Hard materials
(e.g., iron, stone) do not get easily scratched or broken.
Soft materials
(e.g., cotton, rubber) can be pressed or scratched easily.
6. Name three materials that are transparent, translucent, and opaque.
✅ Answer:
Transparent
: Glass, clean water, plastic sheet.
Translucent
: Frosted glass, butter paper, thin fabric.
Opaque
: Wood, metal, stone.
7. What is meant by classification of materials?
✅ Answer:
Classification means grouping materials based on their properties.
It helps in understanding and using materials effectively.
8. Why is glass used for making windows?
✅ Answer:
Glass is
transparent,
allowing light to pass through.
It is
hard and durable,
making it suitable for windows.
9. Why is wood used for making furniture?
✅ Answer:
Wood is
strong and durable.
It can be
cut, shaped, and polished
easily.
10. Why does sugar dissolve in water but sand does not?
✅ Answer:
Sugar is
soluble
because it dissolves in water to form a solution.
Sand is
insoluble
as its particles do not dissolve in water.
11. Why do metals shine?
✅ Answer:
Metals have a property called
lustre
which makes them shiny.
Their surfaces reflect light, giving them a bright appearance.
12. Name two liquids that mix well and two that do not.
✅ Answer:
Mix well
: Water and lemon juice, water and vinegar.
Do not mix
: Water and
oil
, water and kerosene.
13. Why are electrical wires made of copper?
✅ Answer:
Copper is a
good conductor
of electricity.
It is
ductile
and can be drawn into thin wires.
14. Why is rubber used for making tyres?
✅ Answer:
Rubber is
flexible and strong.
It provides
good grip and durability
for tyres.
15. What is the difference between transparent and opaque materials?
✅ Answer:
Transparent materials
allow light to pass through (e.g., glass).
Opaque materials
do not allow light to pass through (e.g., wood).
16. Why do we use plastic containers for storing food?
✅ Answer:
Plastic is
lightweight, waterproof, and durable.
It does not react with food.
17. Why is aluminium used for making utensils?
✅ Answer:
Aluminium is
lightweight and strong.
It is a
good conductor
of heat, making it ideal for cooking.
18. Name three objects that sink and three that float in water.
✅ Answer:
Sink
: Stone, iron nail, glass.
Float
: Wood, paper, plastic bottle.
19. Why do oil and water not mix?
✅ Answer:
Oil is
less dense
than water and does not dissolve in it.
It forms a separate layer on top of water.
20. Why is iron used for making bridges?
✅ Answer:
Iron is
strong and durable.
It can bear
heavy weight and pressure.
21. What is meant by conductivity of a material?
✅ Answer:
Conductivity is the ability of a material to allow
heat or electricity
to pass through.
Metals
are good conductors, while
rubber and plastic
are poor conductors.
22. Name two objects that are rough and two that are smooth.
✅ Answer:
Rough
: Stone, sandpaper.
Smooth
: Glass, polished wood.
23. What are magnetic and non-magnetic materials?
✅ Answer:
Magnetic materials
(e.g., iron, nickel) are attracted to a magnet.
Non-magnetic materials
(e.g., plastic, wood) are not attracted to magnets.
24. Why are iron nails stored in a dry place?
✅ Answer:
Iron reacts with water and oxygen to form
rust.
Keeping it dry prevents rusting and extends its life.
25. Name two soft and two hard materials.
✅ Answer:
Soft
: Cotton, sponge.
Hard
: Stone, metal.
26. Why do metals feel cold when touched?
✅ Answer:
Metals are
good conductors
of heat.
They quickly absorb body heat, making them feel cold.
27. Why do some objects float in water?
✅ Answer:
Objects with
less density than water
float.
Objects with
higher density than water
sink.
28. What happens when salt is added to water?
✅ Answer:
Salt
dissolves
completely in water.
It forms a
solution
without settling at the bottom.
29. Why is water called a universal solvent?
✅ Answer:
Water dissolves
many substances
like salt and sugar.
It helps in chemical reactions and biological processes.
30. What is the difference between natural and synthetic materials?
✅ Answer:
Natural materials
come from plants and animals (e.g., wood, cotton).
Synthetic materials
are made by humans (e.g., plastic, nylon).
