Q. 254.1( 21 Votes )

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Answer :

It is given that metal X is found in nature as sulphide XS. It is used in galvanization of iron articles. For galvanization of iron or steel, zinc coating is used.

Therefore, metal X is zinc.


This sulphide ore can be converted into metal by roasting. A process in which sulphide ores are heated in presence of oxygen and are converted into metal oxide and sulphur dioxide.



Further reduction of zinc oxide to zinc is done by carbon.



OR


(i)Aluminium oxides are known to be amphoteric because they can act as either an acid or a base in an acid-base reaction. Amphoteric compounds refer to these compounds that can react with both acids and bases.


For example, aluminium oxide reacts with hydrochloric acid to give water and aluminium chloride. In this reaction, aluminium oxide plays the role of base.


Aluminium oxide can also react with sodium hydroxide, a base, to give water and sodium aluminate (NaAlO3). In this reaction, aluminium oxide instead plays the role of acid.


(i) An iron strip when dipped in a blue copper sulphate solution turns the blue solution pale green and a brown deposition would be seen on the iron strip.


This happens because iron is more reactive than copper which implies that it will more readily give away electrons. Generally, when a more reactive metal is immersed in an aqueous salt solution of a less reactive metal, a displacement reaction takes place, in which the less reactive metal precipitates out in its original solid form and the more reactive metal forms the aqueous salt solution.


Here, in this case, iron displaces copper to form ferrous sulphate aqueous solution (green) and copper (brown flakes) precipitates out.



(ii) Hydrogen gas is not evolved when most metals react withnitric acid. Nitric acid is a very strong oxidizing agent. So, it oxidizes the hydrogen gas formed during the reaction to form water (H2O) and an oxide of nitrogen (NO, N2O, NO2).


The reaction isas follows



While magnesium and manganese react with very dilute nitric acid to liberate hydrogen gas.


The reaction is as follows



(iii) Calcium does not occur in free state in nature since it's highlyreactive and readily reacts with the surrounding elements to form calcium compounds.


The electron configuration is given by 2:8:8:2


Calcium reacts by losing its two valence electrons. Reactivity of metals increase across the period.This means that the larger the period the higher the reactivity.Calcium is in period 4 making it a very reactive metal. For this reason, it cannot exist in its natural form but readily reacts with elements in the surrounding to form compounds


(iv) Sodium and Potassium are kept immersed under kerosene because they are very reactive. If kept freely in contact with air or water they might explode or catch fire which is extremely dangerous.


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