🌟 Class
7 Science Curiosity – Chapter 4 Solutions
🔩 The
World of Metals and Non-metals | Amresh Academy
📝 🔹 Let Us
Enhance Our Learning
1. Which metal is commonly used to make food
packaging materials as it is cheaper, and its thin sheets can be folded easily
into any shape?
👉 Answer:
(i) Aluminium 🥡
2. Which of the following metal catches fire
when it comes in contact with water?
👉 Answer:
(iv) Sodium 🔥
3. State with reason(s) whether the following
statements are True [T] or False [F].
👉 Answer:
4. Why are only a few metals suitable for making
jewellery?
👉
Example: Gold, Silver
5. Match the uses of metals and non-metals given
in Column I with the jumbled names of metals and non-metals given in Column II.
👉 Answer:
6. What happens when oxygen reacts with
magnesium and sulfur. What are the main differences in the nature of products
formed?
👉 Answer:
- Magnesium
+ Oxygen → Magnesium oxide (basic) 🧪
- Sulfur
+ Oxygen → Sulfur dioxide (acidic) 🌫️
👉 Difference:
- Metal
oxide → Basic
- Non-metal
oxide → Acidic
7. Complete the following flow chart: (Flow
chart depicts burning magnesium)
👉 Answer:
- Starting
material → Magnesium ribbon
- Magnesium
+ Air + Heat → Magnesium oxide (ash)
- Magnesium
oxide + Water → Magnesium hydroxide
- Litmus
test:
- Blue
→
No change
- Red
→
Turns blue
👉 Conclusion:
Solution is basic 🧪
8. You are provided with the following
materials. Discuss which material would be your choice to make a pan that is
most suitable for boiling water and why?
Iron, copper, sulfur, coal, plastic, wood, cardboard
👉 Reason:
- Good
conductors of heat 🔥
- Others
are insulators → not suitable
9. You are provided with three iron nails, each
dipped in oil, water and vinegar. Which iron nail will not rust, and why?
10. How do the different properties of metals
and non-metals determine their uses in everyday life?
👉 Answer:
🔩 Metals:
- Conduct
electricity → wires ⚡
- Conduct
heat → utensils 🍳
- Strong
→
tools 🛠️
- Lustrous
→
jewellery 💎
🌿 Non-metals:
- Poor
conductors → insulation 🚫
- Oxygen
→
breathing 🌬️
- Nitrogen
→
fertilizers 🌱
- Chlorine
→
purification 💧
11. One of the methods of protecting iron from
getting rusted is to put a thin coating of zinc metal over it. Since sulfur
does not react with water, can it be used for this purpose? Justify your
answer.
👉 Reason:
- Sulfur
is brittle ⚠️
- Does
not form protective layer
- Zinc
forms strong coating ✔️
12. An ironsmith heats iron before making tools.
Why is heating necessary in this process?
✍️ 🔹 Very
Short Answer Type Questions
What is malleability?
👉
Ability to be beaten into thin sheets 🔨
Name two metals used to make kitchen utensils.
👉
Aluminium, Copper 🍳
What kind of sound do metals make when struck?
👉
Ringing sound 🔔
(sonorous)
Which metal remains in liquid form at room
temperature?
👉
Mercury 🌡️
What is rusting?
👉
Formation of brown layer on iron 🟤
🧠 🔹 Short
Answer Type Questions
Why are electrical wires usually made of copper
or Aluminium?
👉 Good
conductors + ductile ⚡
What happens when magnesium ribbon burns in air?
👉 White
flame →
magnesium oxide
Why are metals used for making cooking utensils?
👉 Good
heat conductors 🔥
What is ductility? Give two examples of ductile
metals.
Why do we store sodium metal in kerosene?
👉
Prevents reaction with air/water ⚠️
📖 🔹
Descriptive Questions
Explain the difference between metals and
non-metals with examples.
Why does an iron nail rust when exposed to both
air and water?
👉 Needs
oxygen + moisture 🌬️💧
Why are most handles of kitchen tools made from
wood or plastic?
👉
Insulators → prevent burns 🛡️
How does the oxide of sulfur differ from the
oxide of magnesium in nature?
What does the Iron Pillar of Delhi teach us
about ancient Indian metallurgy?
👉
Advanced rust-resistant technology 🏛️
🚀 🔹
Exploring Questions
How do metals and non-metals affect our daily
lives in different ways?
If sulfur is soft, non-sonorous, and poor
conductor, can it be used for making wires? Why or why not?
👉 ❌ No → not
ductile, poor conductor
Why is the discovery of iron considered more
significant in history than copper, despite copper being discovered earlier?
👉 Iron
stronger → better tools ⚔️
Can sulfur be used to prevent rusting of iron
like zinc is used in galvanisation? Why or why not?
👉 ❌ No → no
protective coating
Which materials would you choose to make a pan
for boiling water and why?
👉
Copper/Aluminium → good heat conductors 🔥
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