Important Questions for Class 8 Chapter 4 - Materials : Metals and Non-Metals

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Important questions based on NCERT syllabus for Chapter 4 - Materials : Metals and Non-Metals:

Question-1: How will you prove the nature of metal oxides?

Solution: If we burn a magnesium ribbon, white ash of magnesium oxide is formed. Now by adding little water to white ash we can prepare solution of magnesium oxide. When we dip red litmus paper into this solution it turns blue while when we dip blue litmus paper into this solution colour remains unchanged.
The change in the colour of red litmus to blue indicates the presence of a basic substance. Thus, it proves that metal oxides are basic in nature.

Question-2: Why is it advised not to store pickles and curd in metallic utensils?
Solution: Kitchen utensils are generally made up of metals like iron and aluminium. These metals are quite reactive and due to the reaction between acid present in pickle or curd and the utensil metal, a toxic substance may be formed. This toxic can damage the utensil and can even lead to harmful consequences.

Question-3: Write short notes on 5 metallic properties of Metals.

Solution: Most metal display properties that are characteristic of metals. These properties are called metallic properties. Some of these properties are:
(i) Malleability: The property of a metal to be hammered into sheets.
(ii) Ductility: The ability of a metal to be drawn into wires.
(iii) Sonorous: When a metal is struckl with a hard substance, it produce a loud noise (ting).
(iv) Good Conductors: Due to presence of free electrons, metals are good conductors of heat and electricity.
(v) Lustre: Metals have a shiny appearance as compared to non-metals which have a dull appearance.