Sorting materials into group (part -3) class 6


Sorting materials into group

Q.8. What should we keep in our mind while choosing a material to make an object?
Ans. We should choose a material to make an object depending on its properties, and the purpose for which the object is to be used.

Q.9. Name some properties that can be used for sorting materials.
Ans. The materials are classified on the basis of certain properties such as:
•      Appearance (Shiny or Dull)
•      Hardness or Softness
•      Solubility and Insolubility in water
•      Heaviness or lightness with respect to water (Floating or Sinking)
     •      Transparency (Transparent, Translucent or Opaque)

 Q.10. We can not make a tumbler out of a piece of cloth. Give reason.
Ans. We can not make a tumbler out of a piece of cloth because tumblers are generally used for holding water but a piece of cloth cannot hold it. Water will just leak out of a piece of cloth. 
The materials that we can use to make a tumbler can be glass, plastics, metal or other such material that will hold water.

 Q.11. It would not be wise to use paper-like materials for cooking vessels. Give reason.
 Ans. It would not be wise to use paper-like materials for cooking vessels because they will burn out as soon as they are kept on a burning gas stove.
The materials that we can use to make cooking vessels can be Copper, aluminium, stainless steel etc because such materials can conduct heat very well.

Q.12. What do we mean by the term lustre? Give some examples of lustrous and non-lustrous materials.
Ans. In science, the shiny appearance is indicated by the term ‘lustre’. 

Lustrous materials : Metals (such as Gold, Silver, Copper, Aluminium and Iron), Metal alloys (such as Steel, Stainless steel, Brass, etc.) and Diamond.

Non-lustrous materials : Paper, Cardboard, Wood, Chalk, Cotton, Plastic, Rubber, and Sand.

 Q.13. Why do some metals lose their shine and appear dull? What should we do to check the lustre of metals? 
Ans. Some metals often lose their shine and appear dull because of the action of air and moisture on them.
One should notice the lustre, only on their freshly cut surface or rubbing with sand paper.

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