SOME IMPORTANT CHEMICAL COMPOUNDS-II : BRIEF ANSWERS

ANSWER IN BRIEF

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1. Mention uses of washing soda (sodium carbonate).
   

   ANS: The uses of washing soda are :
   

   
   
   • In the manufacture of glass, soap and paper.
     
   • For softening of hard water.
     
   • For the manufacture of caustic soda, borax, etc.
     
   • For the removal of dirt and grease from clothes.
     
   • As a laboratory reagent.
     

   
   

   
   
2. Write the uses of baking soda (sodium hydrogen carbonate).
   

   ANS: The uses of baking soda are :
   

   
   
   • As an antacid in medicine to remove acidity of stomach.
     
   • In the preparation of baking powder (used in preparing cakes, breads, etc.)
     
   • As a fire-extinguisher.
     
   • As a laboratory reagent.
     

   
   

   
   
3. Describe the manufacture of bleaching powder.
   

   ANS: Bleaching powder is manufactured by Hesenclever process. In this process, chlorine gas is passed over slaked lime, Ca(OH)₂, to obtain bleaching powder.
   
   Ca(OH)_2(aq) + Cl_2(g) ---> CaoCl_2(s) + H₂O_(l)
   

   
   
4. Mention the uses of bleaching powder.
   

   ANS: The uses of bleaching powder are :
   

   
   
   • For making drinking water germ-free.
     
   • As an oxidising agent in industry.
     
   • For bleaching of cotton, linen and wood-pulp.
     
   • For bleaching (removing stains from ) washed clothes in laundry.
     

   
   

   
   
5. Write the uses of Plaster of Paris.
   

   ANS: The uses of Plaster of Paris are :
   

   
   
   • In making toys, idols and casts for statues.
     
   • In preparation of denture castings.
     
   • In bone-setting, i.e. fixing fractured limbs, bone joints, etc.
     
   • For sealing air-gaps in laboratory apparatus during experiments.
     
   • For making black-board chalks,decorative materials,POP false ceilings, cosmetics, etc.
     

   
   

   
   
6. Mention the uses of lime.
   

   ANS: The uses of lime are :
   

   
   
   • As a drying agent for drying of gases like ammonia and alcohols.
     
   • In the manufacture of glass and cement.
     
   • In the manufacture of lime paints.
     
   • For preparing basic lining in furnaces.
     
   • For white washing of walls.
     

   
   

   
   
7. Mention properties of steel.
   

   ANS:
   

   
   
   • The properties of steel depend upon the proportion of carbon added to iron.
   • Its hardness depends on the amount of carbon added to it and its heating time.
   • Soft steel contains 0.1 to 0.4% carbon.
   • Hard steel contains 0.5 to 1.5% carbon.
   • Stainless steel (an alloy containing chromium, nickel and iron) is resistant to air, water(moisture), dilute acids and dilute alkalies.
     

   
   

   
   
8. Mention uses of steel.
   

   ANS:
   

   
   
   • Steel containing 7% - 20% manganese is used for making helmets and machinery for cutting rocks.
   • Steel containing chromium and nickel is used in fabrication of parts of aeroplanes and bicycles.
   • Cobalt steel is used to make permanent magnets.
   • Silicon steel is used to make transformers, electromagnets and pipes for the flow of acid.
   • Stainless steel is used in household vessels, surgical instruments and in rods/plates used in setting fractured bones.