Very short answer questions (V.S.A) : X Chemical reactions and Chemical Equation:FA
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1. Arrange the following metals in the decreasing under of reactivity or electro positive character.
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K Zn Na Fe Pb Cu
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2. Which of them will be a reducing agent a metal or non metal?
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3. Balance the chemical equation
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4. Select the combination reaction from following
(i)KClO3 ® KCl + 3 O2
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5. Select the decomposition reaction from following
(i) 2H2O + O2 ® 2H2 O
(ii) CaCO3 ------Heat------® CaO + CO2
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6. Select the double displacement reaction
(i) BaCl2 + H2SO4 ---® Ba SO4 + H2
(ii) 2KBv + Cl2 ® K Cl2 + Bv2
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7. Fill in the following about reactivity series of metal
(a) the …………………. Metal replaces the ………………. Metal from its salt solution.
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8. Which of the following is not the necessary condition for rusting
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(i) Presence of oxygen (ii) Presence of catalyst (iii) Presence of moisture
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9. Which of the following is required for prevention of corrosion?
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(i) coating of less electropositive metal
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(ii) coating of move electropositive metal
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10. Choose the correct about rancidity
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(i) Rancidity is a reduction process (ii) Rancidity is an oxidation process
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Answers
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1. K > Na > Zn > Fe > Pb > Cu
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2. Non metal
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3. 2 Na(s) +2 H2O ® 2NaOH + 2H2
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4. S + O2 ® SO2
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5. CaCO3 ------Heat® CaO + CO2
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6. BaCl2 + H2SO4 ® Ba SO4 + H2
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7. Strong, Weak
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8. Presence of catalyst
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9. Coating with move electropositive metal
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10. Rancidity is an oxidation process
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See some questions: Short Answer type Question (2 marks)
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1. (i) What happens when aqueous solution of barium chloride is added to aqueous sodium sulphate solution?
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(ii) When silver coloured metal (A) is added to dilute sulphuric acid, solution (B) is formed which is colourless solution and a gas (c) is evolved which is colourless name ‘A’, ‘B’ and ‘C’ and write the equation?
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(iii) An ‘A’ blue coloured crystalline salt on heating decomposes to ‘B’ white substance. W hen in
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blue salt solution, a metal (Zinc) is added, its gives rise to colourless solution ‘C’ wth leaving behind ‘D’ reddish brown metal.
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2. Name the compounds ‘A’, ‘B’, ‘C’ and ‘D’
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(iv) A reaction mixture of chromium Oxide is heated with aluminum powder on strong heating
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3. a. Write the reaction?
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b. Give one application of this reaction?
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(v) Define Rusting?
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4. Give two methods of protection of metal trans rusting.
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5. (i) Rusting is a slow electrochemical process in which hydrated oxide of metal in formed from metal when it comes in with air moisture (ii) By Painting, by galvanization, by tinning
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6. (i) Explains the term ‘corrosion’?
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(ii) Write the chemical reaction of corrosion of Iron?
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(iii) Name two metals which corrodes easily?
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(iv) Aluminum corrodes in moist air but is widely used is making utensils.
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(v) what is galvanization and why do we use Zn for it?\
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7. (i) What is rancidity? Where does it happen
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(ii) what are anti oxidants? Why are they added fat and oil containing food to prevent from rancidity?
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(iii) why do most items puffed with nitrogen.
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Solution:
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1. White precipitate of BaSO4 is obtained. Reaction will be as
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Na2SO4 + BACl2 ----------------® BaSO4 + 2NaCl
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2. A is Zinc, B is ZnSO4 solutions C is H2gas and reactions will be
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Zn (s) + H2SO4 (d) ------------® Zn SO4 (aq) + H2 (g)
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3. A, B, C, and D are respectively-
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CuSO4, 5 H2O, CuSO4, ZnSO4 (aq), Cu (s)
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4. (i)Cr2O3 + 2Al ------® Al2O3 + 2 Cr
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(ii) This reaction is used in termite welding
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5. (i) The process of slow destruction of metals when exposed to air, moisture and pollutant gases , in called as corrasim
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(ii) Fe + 3H2 + 2H2O ------------® Fe2O3 x H2O
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(iii) Formation of green coating on copper and formation of thin layer of oxide on aluminum are example of corrosion.
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(iv) Aluminum forms oxide layer on exposure to air, this oxide layer further checks corrosion.
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(v) Galvanization is a process in which Zinc layer is applied on Iron. It is used to protect iron from rusting.
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6. (i) The oxidative deterioration of oils and fats leading to stinking smell or stale taste is known as rancidity.
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(ii) Anti Oxidants are those chemicals which an addition to fat and oil checks it from rancidityan addition of anti oxidants fatty food is protected from stale.
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(iii) Nitrogen is filled in potato chips & other food to create anaerobic (air free atmosphere) which avoids rancidity.
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