The World of Metals and Non metals Class 7 Questions and Answers Science Chapter 4

Reviewing the Curiosity Class 7 Science Book Solutions Chapter 4 The World of Metals and Non metals Class 7 Question and Answer before exams can boost your confidence.

Class 7 Science Chapter 4 The World of Metals and Non metals Question Answer

Science Class 7 Chapter 4 Question Answer The World of Metals and Non metals

The World of Metals and Non metals Class 7 Question Answer (InText)

Question 1.
Identify the objects that are lustrous in appearance and hard. (Page 43)
Answer:
Objects made from metals such as copper, aluminium, and iron have a shiny appearance and are generally hard in nature.

Question 2.
Are all metals hard and solid? (Page 43)
Answer:
No, not all metals are hard and solid. Sodium and potassium are soft and can be cut with a knife, whereas mercury is a liquid metal at room temperature.

Question 3.
Which objects did you find become flat on beating with a hammer? (Page 43)
Answer:
A piece of copper, an iron nail, and a piece of aluminium become flat when beaten with a hammer.

Question 4.
Can you give some examples of metal sheets? (Page 43)
Answer:
Examples of metal sheets are thin silver foil used on sweets and aluminium foil used for wrapping food.

Question 5.
Where do you find the use of metal wires? (Page 44)
Answer:
Metal wires are used in electrical fittings, ornaments like bangles and necklaces, and musical instruments like veena, sitar, violin, and guitar.

Question 6.
Have you ever seen wires made of coal or sulphur? (Page 45)
Answer:
No, coal and sulphur are not ductile, so wires cannot be made from them.

Question 7.
How is the sound produced when a metal spoon or plate is dropped different from the sound produced by coal or wood? Page 45
Answer:
When a metal spoon or plate is dropped they produce a ringing sound, whereas coal or wood produces a dull sound.

Question 8.
Can you name some metals that are used for making cooking vessels? Why are they used? (Page 46)
Answer:
Metals like copper and aluminium are used for making cooking vessels because they are good conductors of heat.

Question 9.
What type of material is used for making the handle of a screwdriver? (Page 47)
Answer:
The handle of a screwdriver is made of plastic which is a poor conductor of electricity.

Question 10.
Why does an electrician wear rubber gloves and shoes while working? (Page 47)
Answer:
An electrician wears rubber gloves and shoes because rubber is a poor conductor of electricity and protects against electric shock.

Question 11.
Which materials make a bulb glow when tested in the experiment? (Page 48)
Answer:
Materials like iron and copper, which are metals, make the bulb glow.

Question 12.
What do we call materials that allow electricity to pass through them easily? (Page 48)
Answer:
Materials that allow electricity to pass through them easily are called good conductors of electricity.

Question 13.
Under what conditions does an iron object develop brown deposits? (Page 48)
Answer:
An iron object develops brown deposits when it comes into contact with both air and water.

Question 14.
How can rusting of iron be prevented? Page so
Answer:
Rusting of iron can be prevented by painting, oiling, greasing, or coating it with zinc (galvanisation).

Question 15.
That happens when magnesium ribbon burns? (Page 51)
Answer:
When magnesium ribbon burns, it forms a basic oxide that turns red litmus paper blue.

Question 16.
Why is sodium stored in kerosene? (Page 52)
Answer:
Sodium is stored in kerosene because it reacts very quickly with air and water, producing a lot of heat.

Question 17.
What happens when sulphur bums in air? (Page 52)
Answer:
When sulphur burns in air, it forms sulphur dioxide gas, which dissolves in water to form sulphurous acid.

Question 18.
Does sulphur behave with water the same way metals do? (Page 53)
Answer:
No, sulphur does not react with water like metals do.

Question 19.
How do non-metals behave? (Page 53)
Answer:
Non-metals are usually soft, dull, not malleable or ductile, not sonorous, and are poor conductors of heat and electricity. Their oxides are generally acidic.

Question 20.
What are some examples of non-metals?
Answer:
Examples of non-metals are oxygen, hydrogen, nitrogen, carbon, etc.

Question 21.
Are plastic, glass, wood, and rubber classified as metals or non-metals? (Page 53)
Answer:
No, plastic, glass, wood, and rubber are not classified as metals or non-metals because they are not elements.

Question 22.
Why are non-metals important in our lives?
Answer:
Non-metals are important because oxygen is needed for breathing, carbon is needed for life, nitrogen is used in fertilisers, chlorine is used for water purification and iodine is used as antiseptic.

NCERT Class 7 Science Chapter 4 Question Answer The World of Metals and Non metals (Exercise)

Question 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?
(a) Aluminium
(b) Copper
(c) Iron
(d) Gold
Answer:
(a) Aluminium is commonly used to make food packaging materials because it is cheaper and its thin sheets can be easily folded into any shape.

Question 2.
Which of the following metal catches fire when it comes in contact with water?
(a) Copper
(b) Aluminium
(c) Zinc
(d) Sodium
Answer:
(d) Sodium catches fire when it comes in contact with water as it reacts very quickly and releases heat and hydrogen gas.

Question 3.
State with reason(s) whether the following statements are True [T] or False [F],
(a) Aluminium and copper are examples of non-metals used for making utensils and statues.
(b) Metals form oxides when combined with oxygen, the solution of which turns blue litmus paper to red.
(c) Oxygen is a non-metal essential for respiration.
(d) Copper vessels are used for boiling water because they are good conductors of electricity.
Answer:
(a) False. Aluminium and copper are metals and not non-metals which are used for making utensils and statues.
(b) False. Metallic oxides are basic in nature and the solution of which turns red litmus paper to blue.
(c) True
(d) False. Copper vessels are used for boiling water because copper is a good conductor of heat, not electricity.

Question 4.
Why are only a few metals suitable for making jewellery?
Answer:
Only a few metals like gold and silver are suitable for making jewellery because they are shiny, do not corrode easily, and can be shaped into beautiful designs.

Question 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.

Column I	Column II
Used in electrical wiring	(a) ENXYGO”
Most malleable and ductile	(b) NECOHIRL
Living organisms cannot survive without it.	(c) PEPORC
Plants grow healthy when fertilisers containing it are added to the soil.	(d) TENGOINR
Used in water purification	(e) OGDL

Answer:
(i)-(c), (ii)-(e), (iii)-(a), (iv)-(d), (v)-(b)

(i) Used in electrical wiring – (c) Copper
(ii) Most malleable and ductile – (e) Gold
(iii) Living organisms cannot survive without it-(a) Oxygen
(iv) Plants grow healthy when fertilisers containing it are added to the soil – (d) Nitrogen
(v) Used in water purification – (b) Chlorine

Question 6.
What happens when oxygen reacts with magnesium and sulphur? What are the main differences in the nature of products formed?
Answer:
When oxygen reacts with magnesium, a white ash of magnesium oxide is form which is basic in nature.
When oxygen reacts with sulphur, sulphur dioxide gas is form which is acidic in nature. Thus, magnesium forms a basic oxide while sulphur forms an acidic oxide.

Question 7.
Complete the following flow chart.

Answer:

Question 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 sulphur coal plastic wood cardboard
Answer:
I would choose copper to make a pan for boiling water because it is a good conductor of heat and heats water quickly and evenly.

Question 9.
You are provided with three iron nails, each dipped in oil, water and vinegar. Which iron nail will not rust, and why?
Answer:
The iron nail dipped in oil will not rust because oil prevents air and water from reaching the surface of the iron and stops rusting.

Question 10.
How do the different properties of metals and non-metals determine their uses in everyday life?
Answer:
Metals are used in everyday life for making utensils, wires, tools, and machines because they are strong, shiny, and good conductors of heat and electricity, while non-metals are used for making fertilisers, medicines, and supporting life because they are either non-reactive or essential for living beings.

Question 11.
One of the methods of protecting iron from getting rusted is to put a thin coating of zinc metal over it.” Since sulphur does not react with water, can it be used for this purpose? Justify your answer.
Answer:
Sulphur cannot be used for protecting iron from rusting because it does not form a protective layer on iron, whereas zinc forms a strong protective layer and prevents iron from coming in contact with air and moisture.

Question 12.
An ironsmith heats iron before making tools. Why is heating necessary in this process?
Answer:
An ironsmith heats iron before making tools because heating makes the iron soft and easier to shape into the desired form.

Class 7 The World of Metals and Non metals Question Answer (Activities)

Activity 1 (Page 42)

Aim To observe the appearance, hardness, and effect of hammering on different materials.
Materials Required Waste pieces of copper and aluminium, an iron nail, a piece of coal, a lump of sulphur (pea-sized), a wooden block, and hammer.

Procedure

1. Take the samples of copper, aluminium, iron nail, coal, sulphur, and wood.
2. Observe each material for appearance (lustrous or non-lustrous) and hardness (hard or soft).
3. Now place each material one by one on a hard surface and gently beat it with a hammer.
4. Note if the object flattens or breaks into pieces.
5. Record all observations in the table.

Observation

Object/ Material	Appearance (Lustrous/ Non-lustrous)	Hard/Soft	Effect of Hammering (Flattens/ Breaks)
Piece of copper	Lustrous	Hard	Flattens
Piece of aluminium	Lustrous	Hard	Flattens
Iron nail	Lustrous	Hard	Flattens
Piece of coal	Non-lustrous	Soft	Breaks into pieces
Lump of sulphur	Non-lustrous	Soft	Breaks into pieces
Block of wood	Non-lustrous	Soft	Breaks into pieces or dents

Conclusion:
Metals like copper, aluminium, and iron are lustrous, hard, and can be flattened when hammered. This shows they are malleable. Non-metals like coal, sulphur, and wood are non-lustrous, soft, and break when hammered.

Viva Questions
1. Which materials became flat when hammered?
2. What do we call the property that allows metals to be flattened?

Activity 2 (Page 45)

Aim To observe and compare the sounds produced by different materials when dropped.
Materials Required Metal spoon, coin, piece of coal, and block of wood.

Procedure

1. Take a metal spoon, a coin, a piece of coal, and a wooden block.
2. Drop each item one by one from a certain height onto a hard surface.
3. Listen carefully to the sound produced by each item.
4. Compare whether the sound is ringing or dull.

Observation

Object/Material	Type of Sound Produced (Ringing/Dull)	Sonorous (Yes/No)
Metal spoon	Ringing	Yes
Coin	Ringing	Yes
Coal	Dull	No
Wood	Dull	No

Conclusion:
We conclude that objects made of metals like the spoon and coin produces a ringing sound and are called sonorous. Non-metals like coal and wood produces dull sounds and are not sonorous.

Viva Questions
1. What kind of sound do metals produce when dropped?
2. What is the term used for materials that produce a ringing sound?

Activity 3 (Page 46)

Aim To compare the ability of different materials to conduct heat.
Materials Required Glass tumbler, hot water, metal spoon, and wooden spoon.

Procedure

1. Place a glass tumbler on a table and fill it with hot water.
2. Take a metal spoon and a wooden spoon of the same size and thickness.
3. Immerse both spoons in the hot water at the same time.
4. Leave them undisturbed for a few minutes.
5. Carefully touch the upper end of each spoon and note which one feels hotter.

Observation

Material of Spoon	Upper End Feels Hot?	Heat Conducted Vdll?
Metal	Yes	Yes (Good conductor)
Wood	No	No (Poor conductor)

Conclusion:
We conclude that the metal spoon gets hotter than the wooden spoon, which shows that metals are good conductors of heat, while wood is a poor conductor.

Viva Questions
1. Why are cooking vessels made of metal but handles made of wood or plastic?
2. Is wood a good conductor of heat?

Activity 4 (Page 47)

Aim To test the electrical conductivity of various materials using a simple circuit.
Materials Required Aluminium foil, iron nail, lump of sulphur (pea-sized), copper wire, piece of coal, dry wood, stone, eraser, and nylon rope.

Procedure

1. Design a simple electric circuit like the tester shown in the chapter “Electricity: Circuits and their Components.”
2. Insert each of the given materials into the circuit one by one.
3. Observe whether the bulb glows or not when the material is added.
4. Record the results in the table.

Observation

Object/Material	Bulb Glows (Yes/No)	Conductor Type
Aluminium foil	Yes	Good conductor
Iron nail	Yes	Good conductor
Copper wire	Yes	Good conductor
Sulphur (pea-sized)	No	Poor conductor
Coal	No	Poor conductor
Dry wood	No	Poor conductor
Stone	No	Poor conductor
Eraser	No	Poor conductor
Nylon rope	No	Poor conductor

Conclusion:
We conclude that materials like aluminium, iron, and copper allowed the bulb to glow, so they are good conductors of electricity. Other materials did not let the bulb glow, so they are poor conductors.

Viva Questions
1. Which materials made the bulb glow in the circuit?
2. What do we call materials that allow electricity to flow easily?

Activity 5 (Page 49)

Aim To find out the conditions necessary for rusting of iron.
Materials Required Clean iron nails, thread, sandpaper, three dry glass bottles (A, B, C), silica gel, boiled and cooled water, oil, and water.

Procedure

1. Take three clean iron nails. If needed, clean their surface using sandpaper.
2. Tie each nail with a thread.
3. In Bottle A, place one iron nail and add silica gel. Close the lid tightly.
4. In Bottle B, place another nail and fill the bottle with boiled and cooled water, then pour a layer of oil on top. Close the lid tightly.
5. In Bottle C, place the third iron nail and add ordinary water so the nail is partially dipped. Leave this bottle open.
6. Keep all bottles undisturbed at room temperature for 8-10 days.
7. Record observations in the table.

Observation

Glass Bottle	Conditions	Presence of Water	Presence of air	Observations
A	Dry air using silica gel	No	Yes	No rust formed
B	Boiled waler + oil layer (no air)	Yes	No	No rust formed
C	Water and air present (open bottle)	Yes	Yes	Rust is formed

Conclusion:
We conclude that rusting occurs only when both air and water are present. Moist air is necessary for the formation of rust on iron.

Viva Questions
1. What is the brown substance formed on iron called?
2. How can rusting of iron be prevented?

Activity 6 (Page 51)

Aim To observe what happens when magnesium burns in air and to test the nature of the product formed.
Materials Required Magnesium ribbon (3-4 cm), sandpaper, spirit lamp or candle, tongs, watch glass, warm water, red and blue litmus papers.

Procedure

1. Take a 3-4 cm long magnesium ribbon and clean it by rubbing with sandpaper.
2. Hold the ribbon with a pair of tongs.
3. Light the other end using a spirit lamp or candle.
4. Let it burn completely. Collect the white ash formed in a watch glass.
5. Add a few drops of warm water to the white powder and stir well.
6. Test the solution using red and blue litmus papers.

Observation

Substance	Litmus Used	Colour	Nature of the Substance
Magnesium oxide	Red litmus paper	Turns blue	Basic
Magnesium oxide	Biue litmus paper	No change	–

Conclusion:
We conclude that magnesium burns in air with a dazzling white flame and forms magnesium oxide, which is basic in nature. This shows that metal oxides are generally basic.

Viva Questions
1. What is the white powder formed after burning magnesium?
2. What is the nature of magnesium oxide?

Activity 7 (Page 52)

Aim To observe the nature of the product formed when sulphur is burned and dissolved in water.
Materials Required Powdered sulphur, deflagrating spoon (or improvised one), candle or spirit lamp, gas jar or glass tumbler with lid, water, and acid-base indicator (like litmus paper).

Procedure

1. Take a small amount of powdered sulphur in a deflagrating spoon (or a similar improvised setup).
2. Heat it until the sulphur starts burning.
3. Immediately introduce the burning sulphur into a gas jar or tumbler and cover it with a lid.
4. After 3-4 minutes, remove the spoon and add a small amount of water into the jar.
5. Quickly cover the jar again and shake it so that the gas dissolves in water.
6. Test the solution using an acid-base indicator like red or blue litmus paper.

Observation

Substance Fonned	Litmus Used	Colour Change	Nature of the Substanc
Sulphur dioxide + H2O	Blue litmus paper	Turns blue	Aasic
Sulphur dioxide + H2O	Red litmus paper	No change	–

Conclusion:
We conclude that burning sulphur forms sulphur dioxide gas, which when dissolved in water, forms sulphurous acid. The solution is acidic in nature, as shown by the change in litmus colour. Unlike metals, sulphur forms acidic oxides.

Viva Questions
1. What is the nature of sulphur dioxide solution in water?
2. Does sulphur behave like a metal in water?

Activity 8 (Page 53)

Aim To observe the behaviour of sulphur when mixed with water and understand the properties of non-metals.
Materials Required Sulphur powder, glass tumbler, and water.

Procedure

1. Take some sulphur powder in a clean glass tumbler.
2. Add a small amount of water to it.
3. Observe whether any change or reaction takes place.

Observation

Substance	Added to	Reaction Observed	Nature of the Substance
Sulphur powder	Water	No visible reaction	Non-metal

Conclusion:
We conclude that sulphur does not react with water. This shows that non-metals like sulphur behave differently from metals in air and water. Non-metals are usually soft, dull, non-malleable, non-ductile, not sonorous, and poor conductors of heat and electricity. Their oxides are acidic in nature.

Viva Questions
1. Does sulphur react with water?
2. Why is phosphorus stored in water?