Popular Chemistry Online: Chemical reactions and equations -important questions with answer

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Thursday, February 18, 2021

Chemical reactions and equations -important questions with answer

MULTIPLE CHOICE QUESTIONS

1.        Barium chloride on reacting with ammonium sulphate forms barium sulphate and ammonium chloride. Which of the following correctly represents the type of the reaction involved?

         (a) Displacement reaction

          (b) Decomposition reaction

          (c )    Combination reaction

          (d)  Double displacement reaction

2. Chemically rust is

  (a)  ferric sulphate

            (b)  ferric oxide 

           (c)hydrated ferrous oxide

          (d) hydrated ferric oxide

 3.    When green colour ferrous sulphate crystals are heated, its colour changes as

                 (a)  it is decomposed to ferric oxide

                       (b)  it loses water of crystallisation

                        (c)  it forms SO2

                        (d)  it forms SO3

            FILL IN THE BLANKS

           4.        Precipitation reactions are type of         

            5.        Decomposition of calcium carbonate forms and .

            6.        Magnesium ribbon is rubbed with sand paper to remove .

          ONE MARK QUESTIONS

            7.        Name the gas produced by the action of dilute hydrochloric acid on zinc granule.

                8.        Which gas is used to prevent rancidity in potato chips packets?

                9.        Write one equation to represent thermal decomposition.

            ASSERTIONS AND REASON

              For the question numbers 10, 11 and 12, two statements are given- one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:

                (a) Both A and R are true and R is the correct explanation of A.

                (b) Both A and R are true but R is not the correct explanation of A.

                (c) A is true but R is false.

                (d) A is false but R is true.

            1.        Assertion: Colour of copper sulphate solution does not change when the iron nail is kept in it.                Reason: Iron is more reactive than copper and displaces it.

            2.        Assertion: Combustion reaction is also called an exothermic oxidation reaction.                                       Reason:   In this reaction oxygen is added and heat energy is released.

            3.        Assertion: Pungent smelling gas is produced when sulphur burns in air. Reason: Sulphur dioxide is formed on the reaction of sulphur with oxygen.

FIVE MARK QUESTIONS

1.         (a) Barium chloride reacts with aluminium sulphate to give aluminium chloride and barium sulphate.

(i)  State the type of reaction.

(ii)  Translate the above statement into a balanced chemical equation.

(b) A metal ‘X’ acquires a green colour coating on its surface on exposure to air.

(i)  Identify the metal ‘X’ and name the process responsible for this change.

(ii)  Name and write the chemical formula of the green colour coating formed on the surface of the metal.

2.         2g of Ferrous Sulphate crystals are heated in a boiling tube.

(i)  State the colour of Ferrous Sulphate crystals both before heating and after heating.

(ii)  Name the gases produced during heating.

(iii)  Write the chemical equation for the reaction.

(b) Describe an activity to show a decomposition reaction in which light is used to decompose a reactant. Write the chemical equation of the reaction and state one of its uses.

3.         (a)Why is it essential to balance a chemical equation?

(b) With the help of a chemical reaction, explain the decomposition of lead nitrate. 

(c)Can rusting of iron take place in distilled water? Give a reason.

(d)  Give two methods to prevent rancidity.

(e)   How will you test for the gas which is liberated when HCl reacts with an active metal?


4.         CASE- STUDY

Answer question numbers 20 (a) to 20 (d) based on your understanding of the following paragraph and the related studied concepts.

A strip of metal X is immersed in the aqueous solution  of salt  YSO4.  After some time a layer  of metal Y  from the salt solution is deposited on the strip of X. Whereas the metal X is used    for galvanisation and metal Y is used in electrical cables.

(a) Identify the metal X. (b)What could be the metal Y? (c)Can you name the salt YSO4?

(d)Represent the above change in the form of a chemical equation.

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