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CLASS - 10 SCIENCE IMPORTANT QUESTIONS OF MARK 5   FOR BOARD EXAMINATION

QUESTION NO. 7

(i) write the step involved in the extraction of pure metal in the middle of activity series from their carbonate ore.

(ii) how is copper extracted from its sulphide Ore? Explain the various steps supported by chemical equation.

 (iii) explain the process of electrolytic refining of copper.

ANSWER NO.7


(i) the metals in the middle of the activity series such as iron, lead and copper are moderately reactive. These are usually presented as sulphide or carbonate in nature.
         Carbonate Ores are changed into oxides by heating strongly in limited air. This process is known as calcination of the chemical reaction of calcination of carbonate ore are as follows -
     ZnCO3 ------------------> ZnO + CO2
              The metal oxide are then reduced to metal by using suitable reducing agent such as copper, when zinc oxide is heated with carbon, it is reduced to metallic zinc.
        ZnO + C ------> Zn + CO

 (ii) which is found as cu2s in nature can be obtained from its Ore by heating in air.
       2Cu2S + 3O ---------------> 2CuO + 2SO2
       2CuO + 2Cu2S --------> 6Cu + SO2

 (iii) copper is refined electrolytically. In this process the impure metal is made at the anode and a thin strip of pure metal is made at cathode. A solution of the metal salt is used as electrolyte. On passing the current through the electrolyte, the pure metal from the anode dissolve into the electrolyte. And equivalent amount of pure metal from the electrolyte is deposit on the cathode. The soluble impurities goes into the solution, where as the insoluble impurities settled down at the bottom of the anode and have known as anode mud.

QUESTION NO.8


Write the chemical formula and name of compound is the active ingredient of all the alcoholic drinks. List its two uses. Write chemical equation and name of the product formed when this compound reacts
(i) sodium metal 
(ii) hot concentrated sulphuric acid.

ANSWER NO.8


Ethanol is a liquid at room temperature. It is commonly called alcohol and it is the active ingredient of all alcoholic drinks.
           Chemical Name - Ethanol
           Chemical formula - CH3CH2OH

UESES

  • Because it's good property of solvent it is used in cough syrup, tincture iodine etc
  • Used as fuel. Ethanol burns cleanly to form carbon dioxide and water.

REACTION WITH SODIUM 


    2Na + 2CH3CH2OH -----------> 2CH3CH2Na + H2

REACTION WITH HOT CONCENTRATED SULPHURIC ACID


 CH3CH2OH ----------------> CH2 = CH2 + H2O

 Reaction gives unsaturated hydrocarbon. Heating ethanol at 443K with excess concentrated sulphuric acid result in ethene.

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