CBSE  /  Class 12  /  Chemistry  /  General Principles and Processes of Isolation of Elements

  • 1. 
    How do we separate two sulphide ores by froth floatation method?

  • By using excess of pine oil
  • By adjusting proportion of oil to water or using depressant.
  • By using some solvent in which one of the sulphides is soluble
  • By using collectors and froth stabilisers like xanthates

  • 2. 
    Common impurities present in bauxite are

  • CuO
  • ZnO
  • CaO
  • SiO

  • 3. 
    An ore of tin containing FeCrO

  • gravity separation
  • magnetic separation
  • froth floatation
  • leaching

  • 4. 
    Which of the following ores cannot be concentrated by magnetic separation?

  • Haematite
  • Malachite
  • Magnetite
  • Siderite

  • 5. 
    The significance of leaching in the extraction of aluminium is

  • 6. 
    from the bauxite ore

  • 7. 
    Which of the following metals is extracted using a silica lined convertor?

  • Mg
  • Al
  • Cu
  • Zn

  • 8. 
    Which of the following sulphides when heated strongly in air gives the corresponding metal without undergoing separate reduction of oxide?

  • Cu
  • FeS
  • HgS
  • ZnS

  • 9. 
    Which of the following metals cannot be obtained by reduction of its metal oxide bv aluminium ?

  • Cr
  • Mn
  • Fe
  • Mg

  • 10. 
    Heating pyrites to remove sulphur is called

  • smelting
  • calcination
  • liquation
  • roasting
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