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1. Write the uses of metals and non-metals in our daily life.
2. How do chemical properties of metals and non-metals differ?
3. How do physical properties of metals differ from those of non-metals?
4. Describe the different methods used for preventing rusting of iron.
5. Iron is more reactive than copper. Can you write an activity to show this?
[NCERT EX
6. Give reasons for the following.
(a) There is a metal grill on the back of a fridge.
(b) Copper wires are commonly used in household cables.
(c) Graphite is used for making electrodes.
(d) Silver articles become black after some time when exposed to air.
7. State whether a displacement reaction will occur if the following are reacted. Give reasons.
(a) Copper sulphate and magnesium
(b) Zinc sulphate and copper
(c) Zinc sulphate and aluminium
(d) Iron sulphate and zinc
(e) Magnesium chloride and aluminium
Answers
Answer:
(1) Copper is used for making electrical wires, cooking utensils, etc. Zinc is mainly used as a protective coating for iron. Aluminium is used for making electrical cables, packaging, cooking utensils, etc. Non-metals Hydrogen is used for the synthesis of ammonia and methyl alcohol, in welding torches, etc.
(2) Metals have 1,2or 3 electrons in the valence shell. So Can lose electrons easily. They are not easily corrodible. Non metals have more than 4 electrons in their valence shell.Non-metals have no reaction with water. Metals react with oxygen to form basic oxides. ... Non-metals react with oxygen to form oxides. Non- metal oxides are soluble in water.
(3) Considering the properties of non-metals it is not shiny, malleable or ductile nor are they good conductors of electricity. ... Properties of Non-metals have less in common with each other than metals. Their physical and chemical properties vary widely. Some non-metals are solids and some are gases at room temperature.
(4) Many different types of coatings can be applied to the surface of the exposed metal in order to prevent corrosion. Common examples of coatings that prevent corrosion include paints, wax tapes, and varnish. Galvanization is the process of applying a protective layer of zinc on a metal.
(5) You see that a reaction takes place and copper is left by itself. Now, we can say that iron has displaced copper from copper sulphate. In such a reaction, the more reactive metal displaces the less reactive metal. Thus, the above activity shows that iron is more reactive than copper.
(6) :-
(a) There is a metal grill behind the fridge for better heat transfer.It increases the surface area ,as a result heat transfer rate also increases. For better heat transfer .
(b)Copper electrical wires are safer to use than wires made of most other conductive metals because they are resistant to heat. As you can see, copper is the preferred metal for electrical wires for several reasons. It has high electrical conductive; it's inexpensive; it's ductile; and it's thermal resistant.
(c) Graphite is used as an electrode because it conducts electricity without taking part in the chemical reaction.
(d) The silver article becomes black after sometimes when exposed to air because silver reacts with sulphur which is present in the atmosphere and then forms silver sulphide. Thus the layer of this silver sulphide is formed on the surface of the silver article so they appear as dull or black.
(7) :-
(a)Copper sulphate and Magnesium:
Yes, displacement reaction takes place as magnesium is more reactive than copper
(b)Zinc sulphate and copper:
No, displacement reaction wont take place as copper is less reactive than zinc.
(c)Zinc sulphate and aluminium:
Yes, displacement reaction takes place as aluminium is more reactive than zinc
(d)Iron sulfate and zinc
Yes, displacement reaction takes place as zinc is more reactive than iron.
(e)Magnesium chloride and aluminium
No, displacement reaction wont take place as aluminium is less reactive than magnesium.
Explanation:
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