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Important questions based on NCERT syllabus for Chapter 4 - Sorting Materials into Groups:
Question-1: Karan read that iron, aluminium, gold, silver and zinc are metals. He is puzzled why all of these are called as metals. Help Karan to figure out the reason behind this by giving a suitable explanation.?
Solution: Materials are grouped together if they exhibit common properties. Metal is the name of a group consisting of elements which have certain common properties like shiny surface, hardness, high electrical conductivity etc. Iron, aluminium, gold, silver and zinc exhibit all these properties so they are termed as metals.
Question-2: Akash wants to make an aquarium. He has two materials – glass and paper. He is confused about which material to use to make the aquarium. Can you help him in deciding which material to choose for making an aquarium? Justify your answer.
Solution: Aquariums are used to store fishes in an aquatic environment which includes water as a major component and in ample quantity. Also, the fishes need to be visible to the people viewing from outside. Now, let’s take a look at the materials based on these requirements.
Water holding capability – Glass has a hard surface and can be moulded into tough slabs whereas paper has a soft surface and cannot hold water. So, glass is a more suitable material to hold water for an aquarium.
Visibility – Glass is transparent whereas paper is opaque, so using paper would be a bad idea as we need to view the fishes also.
Also, paper absorbs water which might create a problem if we try to store water.
Question-3: Rohan went to Germany by a ship. He came to know that the ship is made of iron and concluded that iron floats on water. Do you think that Rohan is right?
Solution: If a material has density less than water, it will float on water. Iron is a metal and metals have very high density because of which they cannot float on water. Ships made of iron float on water because of their structure. The principle behind their floating is Archimedes’ Principle. So, Rohan’s conclusion is not correct because a piece of iron will sink in water