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Metal and Non Metal : Practice Questions


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2 Mark questions

1. Name two solid metals and two solid non - metals along with their symbols.


2. Give reason for the following :           

(a) School bells are made up of metals.           

(b) Electrical wires are made up of copper.


3. Give reason for the following :           

(a) Sodium metal is kept immersed in kerosene.           

(b) Blue colour of copper sulphate solution disappear when some aluminium powder is a added in it.


4. Define the term 'amphoteric oxide'. Give its two examples.


5. Give reason as to why copper is used to make hot water tanks and not steel. (an alloy of iron)


6. A shiny brown coloured metal 'X' on heating in air becomes black in colour. name the black coloured compound formed  and identify 'X'.


7.  (a) Name two metals which evolve hydrogen gas with nitric acid.           

(b) Write product of any one of the metals.


8. Can we palce silver nitrate in an iron vessel ? Give reason for your answer with a balanced chemical equation.


9. Out of the two metals P and Q, P is less reactive than Q, Suggest an activity to arrange these metals in the order of their decreasing reactivity. Support your answer with a suitable chemical equation.


10. (i) Why metals like Cu, Al etc. become dull in appearance after some time ?             

(ii) Name the compound formed on the surface of copper which makes it dull.


11. Name two metals which are found in nature in the free state.


12. Justify the statement – 'All ores are minerals but all minerals are not ores'. Give one example which can be called both ore and mineral.


13. What is 'Thermite welding' ? Give balanced chemical equation of reaction involved in this process.


14. Can  we take anode made up of pure metals and cathode made up of impure metal during electro - refining ? Justify your answer.


15. Give composition of the alloy – 'brass' and 'branze'.


16. What is meant by corrosion ?             

(i) Why do aluminium sheets not corrode easily ?             

(ii) Why is copper vessel covered with a green coating in rainy season ?


17. What do you mean by 'galvanisation' ? Why it is done ?


18. Give reason why :             

(a) Electrical wires are coated with plastic.             

(b) It is necessary to paint iron grills frequently.             

(c) Aluminium is not found in native state.


19. Pure iron is soft and stretches easily when hot.             

(a) How do these property of iron change when :             

(i) small amount of carbon is mixed with it ? 

(ii) nickel and chromium are mixed with it ?             

(b) Define an alloy. How is an alloy prepared ?             

(c) An alloy has low melting point and is therefore used for electrical fuse. Name the alloy and write its constituents.

 

Solutions

1. Solid metals :  (i) Gold (Au), (ii) Silver (Ag).

Solid non - metals : (i) Carbon (C), (ii) Sulphur (S).


2. (a) Metals are sonorous, so school bells are made up of metals.           

(b) Copper is a very good conductor of electricity. So, it is used for making electrical wires.


3. (a) Sodium reacts so vigorously with air that it catches fire if kept in the open. Hence, to protect it and to prevent accidental fires, it is kept immersed in kerosene oil.

(b) Aluminium is more reactive than copper. It displaces copper from copper sulphate solution and forms aluminium sulphate, leaving copper behind. Hence, the colour changes.


4.  An oxide which reacts with acids as well as bases to produce salt and water is called amphoteric oxide.

- Examples : (i) Aluminium oxide (Al2O3), (ii) Zinc oxide (ZnO).


5. Copper and silver are the best conductors of heat. Hence, copper is used make hot water tanks and not steel.


6. Metal 'X' is copper and the black coloured substance is copper (II) oxide.


7. (a) (i) Magnesium (Mg), (ii) Manganese (Mn).           

(b) Magnesium nitrate [Mg(NO3)2]


8. No, we cannot place silver nitrate in an iron vessel because iron is more reactive than silver. It displaces silver from silver nitrate solution and forms ferrous nitrate.           

2AgN{O_3} + Fe \to Fe{\left( {N{O_3}} \right)_2} + 2Ag


9. Activity : In a test tube, a small amount of salt solution of P is taken and metal Q is added into it. Q being more reactive, displaces metal P from its salt solution.           

Chemical equation : Metal Q + Salt solution of P  \to Salt solution of Q + Metal P.


10. (i) Metals like Cu and Al become dull in appearance because of the formation of their oxides on them.             

(ii) Copper (I) oxide (Cu2O)


11. (i) Gold, (ii) Silver.


12. Examples : Minerals – Sodium chloride, magnesium chloride.             

Ore – Sulphide or oxide ores of Pb, Zn etc.


13. Thermite welding involves reaction between aluminium and iron (III) oxide to form aluminium oxide and iron, releasing large amount of heat.             

- Fe2O3 + 2Al  → 2 Fe + Al2O3 + Heat


14. No. Anode is made up of impure metal. On passing the current through the electrolyte, the pure metal from the anode dissolves into the electrolyte.


15. Brass – Cu and Zn             

Bronze – Cu and Tin


16. The surface of some metals, such as iron is corroded when they are exposed to moist air for a long period of time. This phenomenon is known as corrosion.             

(i) Aluminium does not corrode easily because on exposure to air, its surface is coated with a thin layer of aluminium oxide which is protective and non - reactive.             

(ii) It is because copper reacts with moist carbon dioxide in the air and slowly loses its shiny brown surface and gains a green coat.


17. - The process of coating a thin layer of zinc on iron articles is called galvanisation.             

- It is done to prevent corrosion.


18. (a) Electrical wires are made up of copper. Copper reacts with moist carbon dioxide in the air and slowly loses its shiny brown surface and gains a green coat. So, these are coated with plastic.     

(b) To prevent rusting, it is necessary to paint iron grills frequently.             

(c) It is because aluminium is a very reactive element.


19. (a) (i) When a small amount of carbon is mixed, the iron becomes hard and strong.             

(ii) When iron is mixed with nickel and chromium, we get stainless steel.             

(b) Homogeneous mixture of two or more metals or a metal and a non - metal is know as an alloy. It is prepared by first melting the  primary metal, and then, dissolving the other elements in it in define proportions.             

(c) Solde



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