Q11 of 14 Page 97

(a) What is meant by corrosion? Name any two methods used for the prevention of corrosion.

(b) Suppose you have to extract metal M from its enriched sulphide ore. If M is in the middle of the reactivity series, write various steps used in extracting this metal.

(a) What is meant by corrosion? Name any two methods used for the prevention of corrosion.

The unwanted reaction of any metal with its surroundings that deteriorate its qualities is called corrosion. Two methods to prevent corrosion is Painting the metal or alloying it with some other metal in an appropriate ratio.


(b) The first step is to separate dust like and other such physical impurities from the ore. The process is called concentration of the ore. Then following steps are carried out:


First of all sulfide ores are subjected to roasting which converts them into metal oxides.


>>> Roasting(heating in excess air)


The metal oxide is then heated with carbon or coke which is a good reducing agent and converts oxide into pure metal.


>>>> Reduction with coke


The pure metal is then refined to get an ultra pure metal.



Extraction of moderate reactive metals


More from this chapter

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8

Four metal A, B, C and D are added to the following aqueous solutions one by one. The observations made are tabulated below:


Answer the following questions based on the above observations:


(a) Which is the most active metal and why?


(b) What would be observed if B is added to a solution of copper (II) sulphate and why?


(c) Arrange the metal A, B, C and D in order of increasing reactivity.


(d) The container of which metal can be used to store both zinc sulphate solution and silver nitrate solution?


(e) Which of the above solutions can be easily stored in a container made up of any of these metals?

 9

Sample of five metals ‘A’, ‘B’, ‘C’, ‘D’ and ‘E’ was taken and added to the following solution one by one. The results obtained have been tabulated as follows.


Use the above table to answer the following questions about the given metals.


(a) Which of them is most reactive and why?


(b) What would you observe if ‘B’ is added to CuSO4?


(c) Arrange ‘A’, ‘B’, ‘C’, ‘D’ and ‘E’ in the increasing order of reactivity.


(d) Container of which metal can store zinc sulphate and silver nitrate solution?


(e) Which of the above solution(s) can be stored in a container made of any of these metals and why?

 10

What are alloys? How are they made? Name the constituents and uses of brass, bronze and solder.

 12

Reema’s maid fainted in her house. Reema took her maid to doctor. After check-up Doctor fond she suffered from anaemia Doctor advised her to take vegetables and fruits rich in iron. Doctor gave her some folic acid tablets which contain iron (II) sulphate. Reema helped her maid financially also.

(a) What values are possessed by Reema?


(b) Deficiency of which metal cause anaemia?


(c) What is a formula of folic acid?