SOME IMPORTANT CHEMICAL COMPOUNDS-I : MCQs & SHORT ANSWERS

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MULTIPLE-CHOICE QUESTIONS

SELECT THE CORRECT ALTERNATIVE:

1. What is the chemical formula of washing soda ?
   
   
   
   1. NaHCO₃
   2. Na₂CO₃.10H₂O
   3. Na₂CO₃
   4. Na₂SiO₃
      
   
   
2. What is the chemical formula of soda ash ?
   
   
   
   1. NaHCO₃
   2. Na₂CO₃.10H₂O
   3. Na₂CO₃
   4. Na₂SiO₃
      
   
   
3. Brine is ______.
   
   
   
   1. Na₂CO₃
   2. NaHCO₃
   3. NaCl
   4. Na₂SiO₃
      
   
   
4. Sodium hydrogen carbonate is also known as ______.
   
   
   
   1. sodium carbonate
   2. sodium bicarbonate
   3. brine
   4. washing soda
      
   
   
5. The formula of baking soda is ______.
   
   
   
   1. NaHCO₃
   2. Na₂CO₃.10H₂O
   3. Na₂CO₃
   4. Na₂SiO₃
      
   
   
6. NaHCO₃ is not the formula of ______.
   
   
   
   1. sodium bicarbonate
   2. sodium hydrogen carbonate
   3. baking soda
   4. soda ash
      
   
   
7. What is the chemical formula of bleaching powder ?
   
   
   
   1. Ca(OH)₂
   2. CaCl₂
   3. CaOCl₂
   4. CHCl₃
      
   
   
8. Which substance is a salt of weak acid and strong base ?
   
   
   
   1. Slaked lime
   2. Gypsum
   3. bleaching powder
   4. Washing soda
      
   
   
9. Which of the following is the chemical formula of Plaster of Paris ?
   
   
   
   1. CaSO₄
   2. CaSO₄.1/2 H₂O
   3. CaSO₄.H₂O
   4. CaSO₄.2H₂O
      
   
   
10. The approximate composition of ordinary glass is ______.
    
    
    
    1. Na₂O.CaO.SiO₂
    2. Na₂O.CaO.SiO₃
    3. Na₂CO₃.6SiO₂
    4. Na₂O.CaO.6SiO₂
       
    
    
11. What is the formula of sodium silicate ?
    
    
    
    1. Na₂SiO₂
    2. Na₂SiO₃
    3. Na₃SiO₂
    4. NaSiO₃
       
    
    
12. Lead crystal glass contains ______.
    
    
    
    1. potassium carbonate, lead oxide, silica
    2. sodium carbonate, lead carbonate, silica
    3. potassium carbonate, sodium carbonate, silica
    4. sodium carbonate, lead oxide, silica
       
    
    
13. Pyrex glass is ______.
    
    
    
    1. plasticized glass
    2. polymeric glass
    3. heat-resistant glass
    4. opaque glass
       
    
    
14. Which component gives photochromic glass its properties ?
    
    
    
    1. Silver nitrate
    2. Silver iodide
    3. Silver chloride
    4. Silver bromide
       
    
    
15. Steel is an alloy of ______.
    
    
    
    1. iron and silica
    2. iron and nickel
    3. iron and chromium
    4. iron and carbon
       
    
    
16. Stainless steel contains ______.
    
    
    
    1. iron and carbon
    2. iron, nickel and chromium
    3. nickel and chromium
    4. nickel, chromium and carbon
       
    
    
17. Which steel is used for making transformers and electromagnets ?
    
    
    
    1. Manganese steel
    2. Chromium steel
    3. Cobalt steel
    4. Silicon steel
       
    
    
18. ______ is used for making permanent magnets.
    
    
    
    1. Manganese steel
    2. Chromium steel
    3. Cobalt steel
    4. Silicon steel
       
    
    
19. Helmets are made from ______.
    
    
    
    1. Manganese steel
    2. Chromium steel
    3. Cobalt steel
    4. Silicon steel
       


20. What is used as an antacid ?
    
    
    
    1. Na₂CO₃
    2. NaHCO₃
    3. NaCl
    4. NaOH
       
    
    
21. 
    
    
    
    4. 
       
    
    

ANSWERS TO MCQs

(1) B (2) C (3) C (4) B (5) A (6) D (7) C (8) D (9) B (10) D (11) B (12) A (13) C (14) D (15) D (16) B (17) D (18) C (19) A (20) B

SHORT QUESTIONS

ANSWER IN SHORT:

1. Write the formula of washing soda.
   
        ANS : The formula of washing soda is Na₂CO₃.10H₂O.
   


2. By which process is sodium carbonate manufactured ?
   
        ANS : Sodium carbonate is manufactured by Solvay's Ammonia-soda process.
   


3. The aqueous solution of washing soda turns red litmus paper to blue. True or false ?
   
        ANS : This is a true statement.
   


4. The aqueous solution of washing soda is acidic. True or false ?
   
        ANS : This is a false statement. The aqueous solution of washing soda is basic.
   


5. What is the chemical name of washing soda ?
   
        ANS :The chemical name of washing soda is sodium carbonate decahydrate.
   
6. What is the chemical name of bleaching powder ?
   
        ANS : The chemical name of bleaching powder is Calcium oxychloride.
   


7. By which process is bleaching powder manufactured ?
   
        ANS : Bleaching powder is manufactured by Hesenclever method.
   


8. What is the chemical name of Plaster of Paris ?
   
        ANS : The chemical name of Plaster of Paris is Calcium sulphate hemihydrate.
   


9. Write the chemical formula of Plaster of Paris.
   
        ANS : The chemical formula of Plaster of Paris is CaSO₄.1/2 H₂O.
   


10. What is the chemical formula of gypsum ?
    
         ANS : The chemical formula of gypsum is CaSO₄.2H₂O.
    


11. Why is NaCl added to Plaster of Paris ?
    
         ANS : NaCl is added to Plaster of Paris to increase its setting time.
    


12. What is the chemical name of quick lime ?
    
         ANS : The chemical name of quick lime is calcium oxide.
    


13. What is the chemical formula of slaked lime ?
    
         ANS : The chemical formula of slaked lime is Ca(OH)₂.
    


14. What is the melting point of lime ?
    
         ANS : The melting point of lime is 2000°C.
    


15. What happens when lime is heated in oxy-hydrogen flame ?
    
         ANS : When lime is heated in oxy-hydrogen flame a bright white light called 'lime light' is produced.
    


16. Complete the chemical reaction :
                        2000°C
    

    CaO_(s) + 3C_(s) →

    
    
         ANS :
    
                          2000°C
    CaO_(s) + 3C_(s)   →    CaC_2(s) + CO_(g)
    


17. Who prepared Portland cement for the first time ?
    
         ANS : Joseph Aspdin of England prepared Portland cement for the first time in 1824 AD.
    


18. Why is cement called Portland cement ?
    
         ANS : Cement is called Portland cement because when mixed with water it hardens to a mass resembling Portland rock of England.
    


19. Mention the main constituents of cement.
    
         ANS : Dicalcium silicate, tricalcium silicate and tricalcium aluminate are the main constituents of cement.
    


20. What is the full form of RCC ?
    
         ANS : The full form of RCC is Reinforced Cement Concrete or Reinforced Concrete Cement.
    


21. What are the components of optical glass ?
    
         ANS : The components of optical glass are : potassium carbonate, red lead and silica.
    


22. What is photochromatic glass ?
    
         ANS : Photochromatic glass is the glass which darkens automatically but temporarily when exposed to bright light.
    


23. Mention two forms of glass fibre.
    
         ANS : Glass wool and optical fibres are two forms of glass fibre.
    


24. Mention some pigments used for making coloured glass.
    
         ANS : Ferric oxide, chromium oxide, manganese dioxide, cobalt oxide, etc. are some pigments used for making coloured glass.
    


25. How much carbon does steel contain ?
    
         ANS : Steel contains 0.1 to 1.5 % carbon.
    


26. Mention the proportion of carbon in mild steel and hard steel.
    
         ANS : The proportion of carbon in mild steel is 0.1 to 0.4 % and in hard steel is 0.5 to 1.5 %.
    


27. On what does the hardness and elasticity of the steel depend ?
    
         ANS : The hardness and elasticity of the steel depends on the percentage of carbon present in it and the heat treatment (process of tempering).
    


28. How much manganese does the manganese steel used for making rock crushing machinery contain ?
    
         ANS : The manganese steel used for making rock crushing machinery contains 7 - 20 % manganese.
    


29. Which sodium compound is used to convert hard water to soft water ?
    
         ANS : Sodium carbonate is used to convert hard water to soft water.
    


30. What will be the effect on the crystal of washing soda when it is kept in air ?
    
         ANS : When the crystal of washing soda is kept in air it loses nine molecules of water of crystallization to give sodium carbonate monohydrate.
    


31. Write the chemical reaction when sodium hydrogen carbonate is heated.
    
         ANS :       Δ
    2NaHCO_3(s) → Na₂CO_3(s) + H₂O_(g) + CO_2(g)
    


32. Which compound reacts with chlorine gas to give bleaching powder ?
    
         ANS : Calcium hydroxide (slaked lime) reacts with chlorine gas to give bleaching powder.
    


33. What will be the result if proper care is not taken in heating gypsum (Plaster of Paris) ?
    
         ANS : If gypsum is heated well above 100°C, anhydrous calcium sulphate (CaSO₄) called 'dead burnt plaster' is formed which does not set like Plaster of Paris on adding water.
    


34. Write the equation for chemical reaction between lime and water.
    
         ANS :
    CaO + H₂O → Ca(OH)₂ + Heat
    


35. Which type of glass is used in manufacturing of windows of vehicles ?
    
         ANS : Safety glass is used in manufacturing of windows of vehicles.
    


36. How are coloured glasses manufactured ?
    
         ANS : Coloured glass is manufactured by adding small amount of colouring material like certain metal oxides in the molten state during the preparation of glass.
    


37. Which metals are present in stainless steel alloys ?
    
         ANS : Iron, nickel and chromium are present in stainless steel alloys.
    


38. Write the use of photochromatic glass.
    
         ANS : Photochromatic glass is used for making spectacles, goggles and cameras.
    


39. Which compound shows fluorescence ?
    
         ANS : Washing soda shows fluorescence.
    


40. What is the common name of Na₂CO₃.10 H₂O ?
    
         ANS : The common name of Na₂CO₃.10 H₂O is washing soda.
    


41. What is added during production of bread ?
    
         ANS : Baking powder (along with tartaric acid) is added in the production of bread.
    


42. Write the equation for the reaction between slaked lime and chlorine gas.
    
         ANS :
    
    Ca(OH)₂ + Cl₂ ---> CaOCl₂ + H₂O
    


43. Write the chemical equation for the preparation of quick lime.
    
         ANS :
    
    CaCO₃ <----> CaO + CO₂
    


44. Mention basic substances used in the manufacture of glass.
    
         ANS : Sodium carbonate, potassium carbonate, calcium carbonate, silica, etc. are basic substances used in the manufacture of glass.
    


45. By what common name is anhydrous sodium carbonate known ?
    
         ANS :Anhydrous sodium carbonate is known as soda ash.
    


46. What is the annual production of soda ash in India ?
    
         ANS :About 1.54 lac tons.
    


47. What is 'lime light'?
    
         ANS :When lime is heated in oxyhydrogen flame a bright white light is produced which is called 'lime light'.