ЁЯМЯ Class 7 Science Curiosity – Chapter 4 Solutions
ЁЯФй The World of Metals and Non-metals | Amresh Academy
ЁЯУЭ ЁЯФ╣ 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?
ЁЯСЙ Answer: (i) Aluminium ЁЯеб
2. Which of the following metal catches fire when it comes in contact with water?
ЁЯСЙ Answer: (iv) Sodium ЁЯФе
3. State with reason(s) whether the following statements are True [T] or False [F].
ЁЯСЙ Answer:
4. Why are only a few metals suitable for making jewellery?
ЁЯСЙ 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.
ЁЯСЙ Answer:
6. What happens when oxygen reacts with magnesium and sulfur. What are the main differences in the nature of products formed?
ЁЯСЙ Answer:
- Magnesium + Oxygen → Magnesium oxide (basic) ЁЯзк
- Sulfur + Oxygen → Sulfur dioxide (acidic) ЁЯМл️
ЁЯСЙ Difference:
- Metal oxide → Basic
- Non-metal oxide → Acidic
7. Complete the following flow chart: (Flow chart depicts burning magnesium)
ЁЯСЙ Answer:
- Starting material → Magnesium ribbon
- Magnesium + Air + Heat → Magnesium oxide (ash)
- Magnesium oxide + Water → Magnesium hydroxide
- Litmus test:
- Blue → No change
- Red → Turns blue
ЁЯСЙ Conclusion: Solution is basic ЁЯзк
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
ЁЯСЙ Reason:
- Good conductors of heat ЁЯФе
- 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?
ЁЯСЙ Answer:
ЁЯФй Metals:
- Conduct electricity → wires ⚡
- Conduct heat → utensils ЁЯН│
- Strong → tools ЁЯЫа️
- Lustrous → jewellery ЁЯТО
ЁЯМ┐ Non-metals:
- Poor conductors → insulation ЁЯЪл
- Oxygen → breathing ЁЯМм️
- Nitrogen → fertilizers ЁЯМ▒
- Chlorine → purification ЁЯТз
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.
ЁЯСЙ 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?
✍️ ЁЯФ╣ Very Short Answer Type Questions
What is malleability?
ЁЯСЙ Ability to be beaten into thin sheets ЁЯФи
Name two metals used to make kitchen utensils.
ЁЯСЙ Aluminium, Copper ЁЯН│
What kind of sound do metals make when struck?
ЁЯСЙ Ringing sound ЁЯФФ (sonorous)
Which metal remains in liquid form at room temperature?
ЁЯСЙ Mercury ЁЯМб️
What is rusting?
ЁЯСЙ Formation of brown layer on iron ЁЯЯд
ЁЯза ЁЯФ╣ Short Answer Type Questions
Why are electrical wires usually made of copper or Aluminium?
ЁЯСЙ Good conductors + ductile ⚡
What happens when magnesium ribbon burns in air?
ЁЯСЙ White flame → magnesium oxide
Why are metals used for making cooking utensils?
ЁЯСЙ Good heat conductors ЁЯФе
What is ductility? Give two examples of ductile metals.
Why do we store sodium metal in kerosene?
ЁЯСЙ Prevents reaction with air/water ⚠️
ЁЯУЦ ЁЯФ╣ 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?
ЁЯСЙ Needs oxygen + moisture ЁЯМм️ЁЯТз
Why are most handles of kitchen tools made from wood or plastic?
ЁЯСЙ Insulators → prevent burns ЁЯЫб️
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?
ЁЯСЙ Advanced rust-resistant technology ЁЯПЫ️
ЁЯЪА ЁЯФ╣ 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?
ЁЯСЙ ❌ No → not ductile, poor conductor
Why is the discovery of iron considered more significant in history than copper, despite copper being discovered earlier?
ЁЯСЙ Iron stronger → better tools ⚔️
Can sulfur be used to prevent rusting of iron like zinc is used in galvanisation? Why or why not?
ЁЯСЙ ❌ No → no protective coating
Which materials would you choose to make a pan for boiling water and why?
ЁЯСЙ Copper/Aluminium → good heat conductors ЁЯФе
