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

By tackling these RBSE Solutions Class 7 Science and RBSE Class 7 Science Chapter 4 The World of Metals and Non metals Question Answer, students will build a solid foundation in the topic.

The World of Metals and Non metals Class 7 Question Answer

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

Class 7 Science Curiosity Chapter 4 Question Answer (Exercise)

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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?
(i) Aluminium
(ii) Copper
(iii) Iron
(iv) Gold
Answer:
(i) Aluminium

Question 2.
Which of the following metal catches fire when it comes in contact with water?
(i) Copper
(ii) Aluminium
(iii) Zinc
(iv) Sodium
Answer:
(iv) Sodium

Question 3.
State with reason(s) whether the following statements are True [T] or False [F].
(i) Aluminium and copper are examples of non-metals used for making utensils and statues.
Answer:
False (F), because aluminium and copper are metals, and they have characteristics of metals like malleability, ductility and conduction.

(ii) Metals form oxides when combined with oxygen, the solution of which turns blue litmus paper to red.
Answer:
False (F), because the oxides of metals are of basic nature and their solution does not change colour of blue litmus even they turn red litmus into blue.

(iii) Oxygen is a non-metal essential for respiration.
Answer:
True (T), because oxygen is a non-metal and essential for respiration in living organisms.

(iv) Copper vessels are used for boiling water because they are good conductors of electricity. Answer: False (F), because copper vessels are used for boiling water but not because they are good conductors of electricity but they are good conductors of heat, heat is important here.

Question 4.
Why are only a few metals suitable for making jewellery?
Answer:
Only few metals are suitable for making jewellery because only some metals like gold, silver, platinum are highly ductile They can be turned in any shape, they are lustrous, rust free. Just because these are chosen to make jewellery.

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-I	Column-II
(i) Used in electrical wiring	(a) E N X Y G O
(ii) Most malleable and ductile	(b) N E C O H I R L
(iii) Living organisms without it cannot survive without it	(c) P E P O R C
(iv) Plants grow healthy containing it are added to the soil	(d) T E N G O I N R
(v) Used in water purification	(e) G O L D

Answer:

Column-I	Column-II
(i) Used in electrical wiring	(c) P E P O R C
(ii) Most malleable and ductile	(e) G O L D
(iii) Living organisms without it cannot survive without it	(a) E N X Y G O
(iv) Plants grow healthy containing it are added to the soil	(d) T E N G O I N R
(v) Used in water purification	(b) N E C O H I R L

Question 6.
What happens when oxygen reacts with magnesium and sulfur? What are the main differences in the nature of products formed?
Answer:
Magnesium reacts with oxygen and form magnesium oxide and its solution is of basic nature. Sulfur reacts with oxygen and form sulfur di-oxide and its solution is of acidic nature. So, oxide of metals are basic and non-metals are acidic.

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?

Answer:
Among the above mentioned things iron and copper are most suitable for making pan to boil water because these are metals which are good conductors of heat and solid also. Other things are not useful for making pan to boil water because they are brittle and poor conductors of heat.

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 layer won’t allow air to reach the nail surface, so nail will not come in direct contact with air and water hence does not rust.

Question 10.
How do the different properties of metals and non-metals determine their uses in everyday life?
Answer:
Properties of metal: Malleability – Metals are malleable can be beaten into thin sheets, hence used as aluminium foil, and copper, silver, gold, aluminium and many other in making utensils.

Ductility: Their ductility make them turn into a thin wire, so gold and silver are used in making jewellery and copper wire in electricity and other.

Conduction : Their conductivity with heat and electricity make them useful for making utensils and also in electric tools.

Sonority: Sonority is reason metals are used in temple bells and wires in stringed musical instruments.
Characteristics of non-metals and use in daily life:

Conductivity : They are poor conductors of heat and electricity hence used as handles of cooking utensils and electric tools and plastic and rubber are used as insulator in wires.

Brittle: Non-metals are brittle so used as fertilisers and in medicines in powdered form. Phosphorous in matchsticks, graphite in pencils.

Gaseous : In gaseous form oxygen is a life giving non-metal and nitrogen for plant growth.

Other: Carbon as building block of life forms. Chlorine as water purifier, and iodine solution as an antiseptic.

Question 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.
Answer:
Sulfur is not ductile and malleable and it does not form an anti-rusting layer. In contrast, zinc is solid and anti-rust, so choosen for galvanisation.

Question 12.
An ironsmith heats iron before making tools. Why is heating necessary in this process?
Answer:
Malleability and ductility of iron enhances on heating and make it easy to give a shape accordingly and making tools, so iron is heated extremely before making tools and utensils.

The World of Metals and Non metals Class 7 Questions and Answers (Intext)

(Page No. 43)

Question 1.
Are all metals hard and solid?
Answer:
No, all metals are not solid, some metals like sodium and potassium are so soft that they can be cut with a knife. And a metal mercury which is found in liquid state at room temperature.

Question 2.
Which objects become flat on beating with a hammer?
Answer:
The objects which are malleable become flat on beating with a hammer. Ex. : Metals like piece of copper, piece of aluminium and an iron nail can become flat on beating with hammer.

(Page No. 44)

Question 3.
Where do you find the use of metal wires?
Answer:
We have seen wires of metal like copper or aluminium in electrical fittings. In ornaments like bangles, necklaces, earrings etc. metal wires play an important role. Similarly, metal wires serve a vital function in a variety of stringed musical instruments such as Veena, Sitar, Violin, and Guitar.

(Page No. 45)

Question 4.
Have you ever noticed the sound produced when a metal spoon, or a metal plate, or a metal coin is dropped on the floor? How is it different from the sound produced when a piece of coal or wood is dropped on the floor?
Answer:
We observed that a spoon and the metal coin produce a ringing sound which is called sonority. Coal and wood on the other hand, produce a dull sound.

(Page No. 46)

Question 5.
Can you name some metal that are used for making cooking vessels? Do you know why these metals are used for this purpose?
Answer:
Metals which are used for making cooking vessels are—Iron, steel, aluminium, copper and brass. These are used for this purpose because they are good conductor of heat which helps to cook food well and fast.

Question 6.
Have you ever seen an electrician using screw driver? What type of material is used for making its handle? You may have also noticed the electrician wearing rubber gloves and shoes while working. What can be the reason for this?
Answer:
Screw driver’s handles used by electricians are made of plastic. Electricians wear rubber gloves and shoes while working because rubber and plastic are insulators. So while working with electricity these insulators prevent them from electric shock.

(Page No. 48)

Question 7.
In which conditions would an iron object develop brown deposits?
• When it comes into contact with dry air only.
• When it comes into contact with water only.
• When it comes into contact with both air and water.
Answer:
When it comes into contact with both air and water.