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Chemical Reactions and Equations - Important Questions & Preparation Tips

May 16, 2013 12:30 IST

    In this article you will get the clue that from where and how the questions are being framed from the chapter Chemical Reactions and Equations. Our experts have full confidence that you will not lose any of the questions in the board exam as well as in home exams from this chapter if you will keep the following terms / question in your mind while studying.

    • What are reactants and product of chemical reactions?
    • What are the characteristics of chemical reaction?
    • What will be the product when:

                         Potassium iodide reacts with lead nitrate
                         Sulphuric acid and barium chloride reacts

    • How the color changes when reaction takes place between

                         Citric acid and purple color potassium permagnate
                         Sulphurdioxide and acidified potassium dichromate

    • Why temperature changes in a chemical reaction?
    • Difference between quick lime and slaked lime.
    • Examples of reactions where heat is produced and absorbed.
    • Combustion reaction of candle wax.
    • Short hand method of representing a chemical reaction.
    • Points to remember while balancing a chemical reaction.
    • What are the ways to make chemical equation more informative?
    • Explain the important steps to write balanced chemical equation.
    • What are the various oxides of iron metal?
    • Differentiate between ferrous and ferric oxide?
    • Thermal decomposition.
    • What will be the product when decomposition of FeSO4 takes place?
    • What is the color of ferrous sulphate crystals?
    • What product comes when lead nitrate is heated?
    • Electrolysis of water.
    • Use of decomposition reaction.
    • Oxidizing and reducing agents
    • Displacement reaction, aerial oxidation, rusting and redox reaction.
    • Effect of oxidation on food.
    • How can rancidity prevented.
    • Chemical reaction for digestion in our body.
    • Two examples of each reaction given below:

                           Combination
                           Decomposition
                           Displacement
                           Double displacement

    • Why should magnesium ribbon be cleaned before burning in air?
    • A silver white metal X taken in form of ribbon, when ignited, burns in air with a dazzling white flame to form a white powder Y. when water is added to powder Y, it dissolves partially to form another substance Z.

                           What could metal X be
                           What is powder Y
                           With which substances metal X combines to form powder Y
                           What a substance Z? name one domestic use of substance Z
                           Write a balanced chemical equation of the reactions which takes place when metal X burns in air to form powder Y.

    • A metal salt MX when exposed to light splits up to form metal M and a gas X2. Metal M is used in making ornaments where as gas X2 is used in making bleaching powder. The salt MX is itself used in black and white photography.

                           What do you think metal M is?
                           What could b gas X2
                           Name the metal salt MX
                           Name nay two salt solution which on mixing together can produce a precipitate of salt MX
                           What type of chemical reaction takes place when salt MX is exposed to light? Write the equation of reaction.

    • In the table, the reactants change and form given products. However while changing from reactants to products the change in color takes place. It is very important for students to know which color is changed and which new color is formed.

    Reactants Products
    CuCl2(aq) + Pb(s) PbCl2 + Cu (s)
    2AgNO3 (aq) +Cu(s) Cu(NO3)2 (aq) + 2Ag (s)
    Fe(s) + 2HCl (aq) FeCl2 (aq) + H2(g)
    2FeSO4 (s) Fe2O3 (s)+ SO2 (s) + SO3(g)
    CuSO4(aq) +Zn(s) ZnSO4 (aq) + Cu(s)
    CuSO4 (aq) + Mg (s) MgSO4 (aq) + Cu(s)
    CuSO4 (aq) + Fe(s) FeSO4(aq) + Cu(s)

    There are some sample questios given below :

    1. What is the colour of the precipitate formed when a solution of sodium sulphate is added to a solution of barium nitrate?
      1. Black
      2. Blue
      3. Brown
      4. White
    2. The reaction between iron and copper sulphate in water represents which type of reaction?
      1. Single displacement
      2. Direct combination
      3. Decomposition
      4. Double decomposition
    3. Which one is not observed when a clean nail of iron is added to a solution of copper sulphate in water?
      1. A brown material is deposited on iron nail
      2. After some time blue solution becomes greenish
      3. Blue color of copper sulphate fades
      4. A blue material is deposited on the iron nail
    4. 2FeSO4 (s) --------> Fe2O3 (s) + SO2 (g) + SO3 (g). This reaction is __________ of ferrous sulphate.
      1. Thermal Displacement
      2. Combination 
      3. Thermal Decomposition
      4. Double displacement
    5. Which one is a double displacement reaction?
      1.  BaCl2 + Na2SO4 --------> BaSO4 + 2NaCl
      2.  CaO + H2O ------------> Ca(OH)2
      3.  2Pb(NO3)2 --------> 2PbO + 4NO2 + O2
      4. Zn + 2AgNO3 ----------> Zn(NO3)2 + 2Ag
    6. The mole ratio of Hydrogen and Oxygen gases liberated during electrolysis of water
      1. 1:1
      2. 2:1
      3. 4:1
      4. 1:2
    7. Copper displacement which of the following metals from its salt solution:
      1. ZnSO4
      2. FeSO4
      3. FeSO4
      4. NiSO4
    8. PbS reacts with ozone and forms PbSO4. As per the balanced equation, molecules of ozone required for every one molecule of PbS are
      1. 6
      2. 4
      3. 3
      4. 2
    9. Stale food give bad smell and test because of?
      1. Corrosion
      2. Displacment
      3. Heating
      4. Rancidity
    10. The heating of ferrous sulphate is an example of __________ reaction and the reaction between iron and copper sulphate is an example of __________ reaction.
      1.  displacement, decomposition
      2.  combination, displacement 
      3. decomposition, displacement
      4. combination, decomposition
    11. Which of the following is exothermic process
      1. Reaction of water with quick lime
      2. Dilution of an acid
      3. Evaporation of water
      4. Sublimation of camphor crystals
    12. When dilute hydrochloric acid is added to zinc pieces taken in a test tube:
      1. no change takes place
      2. the colour of the solution becomes yellow
      3. a pungent smelling gas gets liberated
      4. small bubbles of hydrogen gas appear on the surface of zinc pieces
    13. Following is the reactivity series in decreasing order of their reactivity -  Magnesium > Zinc > Iron > Lead > Copper > Silver > Gold  Which one of the following metals can displace copper from copper sulphate solution?
      1. Zn
      2. Ag
      3. Au
      4. None
    14. Which of the following gases can be used for storagin fresh sample of an oil for a long time-
      1. Carbon dioxide or oxygen
      2. Nitrogen or Oxygen
      3. Carbon dioxide or Helium
      4. Nitrogen or Helium
    15. Dissolved sugar is an example of
      1. Physical change
      2. Redox reaction
      3. Chemical reaction
      4. None of the above

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