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Public Model Question Paper Part-III 2019 - 2020

12th Standard EM

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Chemistry

Time : 02:45:00 Hrs
Total Marks : 70

    Part I

    Answer all the questions.

    Choose the most suitable answer from the given four alternatives and write the option code with the corresponding answer.

    15 x 1 = 15
  1. Sulphide ore is converted to oxide form by using the process_________

    (a)

    Calcination

    (b)

    Roasting

    (c)

    Smelting

    (d)

    Leavhing

  2. The geometry at which carbon atom in diamond are bonded to each other is

    (a)

    Tetrahedral

    (b)

    graphene

    (c)

    Fullerene

    (d)

    dry ice

  3. Which of the following is correct?

    (a)

    H3PO3 is dibasic and reducing

    (b)

    H3PO3 is dibasic and non-reducing

    (c)

    H3PO4 is tribasic and reducing

    (d)

    H3PO3 is tribasic and non-reducing

  4. Sc( Z=21) is a transition element but Zinc (z=30) is not becaus

    (a)

    both Sc3+ and Zn2+ ions are colourless and form white compounds

    (b)

    in case of Sc, 3d orbital are partially filled but in Zn these are completely filled

    (c)

    last electron as assumed to be added to 4s level in case of zinc

    (d)

    both Sc and Zn do not exhibit variable oxidation states

  5. Oxidation state of Iron and the charge on the ligand NO in [Fe(H2O)5NO]SO4 are

    (a)

    +2 and 0 respectively

    (b)

    +3 and 0 respectively

    (c)

    +3 and -1 respectively

    (d)

    +1 and +1 respectively

  6. The structure of ionic compound depends upon _________ of the ions.

    (a)

    stoichiometry

    (b)

    Size

    (c)

    both (a) and (b)

    (d)

    neither (a) nor (b)

  7.  If 75% of a first order reaction was completed in 60 minutes , 50% of the same reaction under the same conditions would be completed in

    (a)

    20 minutes

    (b)

    30 minutes

    (c)

    35 minutes

    (d)

    75 minutes

  8. pH of a saturated solution of Ca(OH)2 is 9. The Solubility product ( Ksp) of Ca(OH)2

    (a)

    0.5 ×10-15

    (b)

    0.25 ×10-10

    (c)

    0.125 ×10-15

    (d)

    0.5 ×10-10

  9. When pH of a solution is 2, the hydrogen ion concentration in moles litre-1 is

    (a)

    1 x 10-12

    (b)

    1 X 10-2

    (c)

    1 X 10-7

    (d)

    1 X 10-4

  10. How will you predict whether a reaction is not feasible?

    (a)

    Eocell= -ve

    (b)

    Eocell = +ve

    (c)

    Eocell = 0

    (d)

    Eocell= -ve and Eocell = 0

  11. Statement :
    To stop bleeding from an injury, ferric chloride can be applied. Which comment about the statement is justified?

    (a)

    It is not true, ferric chloride is a poison.

    (b)

    It is true, Fe3+ ions coagulate blood which is a negatively charged sol

    (c)

    It is not true; ferric chloride is ionic and gets into the blood stream.

    (d)

    It is true, coagulation takes place because of formation of negatively charged sol with Cl-.

  12. Addition of water across the double bond of an alkene in presence of sulphuric acid giving alcohol follows ______ rule.

    (a)

    Markownikoff's

    (b)

    anti Markownikoff

    (c)

    Sayt zeff's

    (d)

    Swern

  13. CH3Br \(\overset { KCN }{ \longrightarrow } (A)\overset { { H }_{ 2 }{ O }^{ + } }{ \longrightarrow } (B)\overset { { PCl }_{ 5 } }{ \longrightarrow } \) (C) product (c) is

    (a)

    acetylchloride

    (b)

    chloro acetic acid

    (c)

    \(\alpha\)- chlorocyano ethanoic acid

    (d)

    none of these

  14. Which among the following will from significant amount of meta isomer on nitration?

    (a)

    (b)

    (c)

    (d)

  15. Sprouting barley is the main source of _____sugar.

    (a)

    glucose

    (b)

    fructose

    (c)

    cellulose

    (d)

    maltose

  16. Part II

    Answer any 6 questions. Question no. 24 is compulsory.

    6 x 2 = 12
  17. What is leaching?

  18. Give the uses of Borax

  19. Although \(\triangle\)H of fluorine is less negative than that of chlorine, but fluorine is a stronger oxidising agent than chlorine, why?

  20. What is hydrate isomerism? Give an example.

  21. Explain briefly seven types of unit cell

  22. For a chemical reaction, Variation in the concentration In[A] Vs time in seconds is given as

    (i) What is the order of the reaction?
    (ii) What is the unit of rate constant K?
    (iii) Give the relationship between k and \({ t }_{ \frac { 1 }{ 2 } }\)

  23. Indentify the conjugate acid base pair for the following reaction in aqueous solution
    i) HS- (aq) + HF \(\rightleftharpoons \) F-(aq) + H2S(aq)
    ii) HPO2-+ SO32- \(\rightleftharpoons \) PO43-+HSO3-
    iii) NH4+ CO32-  \(\rightleftharpoons \) NH3+HCO3-

  24. Derive the unit of specific conductance.

  25. What is the major product obtained when two moles of ethyl magnesium bromide is treated with methyl benzoate followed by acid hydrolysis.

  26. Part III

    Answer any 6 questions. Question no. 33 is compulsory.

    6 x 3 = 18
  27. What is coupling of reaction? How is it useful in metallurgy?

  28. Which is the last element in the series of the actinoids? Write the electronic configuration of this element comment on the possible oxidation state of this element.

  29. Explain the IUPAC convention of representing a Galvanic cell

  30. Why are lyophillic colloidal sols are more stable than lyophobilc colloidal sol.

  31. How does glycerol react with KHSO4?

  32. An alkene (A) on ozonolysis gives propanone and aldehyde (B). When (B) is oxidised (C) is obtained. (C) is treated with BriP gives (D) which on hydrolysis gives (E). When propanone is treated with HCN followed by hydrolysis gives (E). Identify A) B) C) D and E.

  33. Outline the preparation of (a) para nitroaniline from aniline, (b) tri bromo benzene from tribromo aniline

  34. Write the monomers of the following sugars and explain how they are linked.
    (i) Sucrose
    (ii) Maltose
    (iii) Lactose

  35. How is Nylon - 6,6 prepared? Give it use.

  36. Part IV

    Answer all the questions.

    5 x 5 = 25
    1. Phenol is distilled with Zn dust followed by friedel – crafts alkylation with prophyl chloride to give a compound B, B on oxidation gives (c) Indentify A,B and C.

    2. Compound (A) with Molecular formula C7H6O does not reduce Fehling's solution. Compound (A) reacts with acetone in the presence of NaOH to give a compound (B) which is an α, β-unsa,turated compound. Further (A) reacts with dimethyl aniline in the presence of cone, H2SO4 to give compound (C) which is a dye. Identify (A) (B) and (C). Explain the reactions.

    1. Write the expression for the solubility product of Hg2Cl2 .

    2. Explain the various chemical methods by which colloids can be prepared.

    1. Ionic solids, which have anionic vacancies due to metal excess defect, develop colour. Explain with the help of a suitable example.

    2. How do nature of the reactant influence rate of reaction.

    1. How are materials classified based on their magnetic properties?

    2. For the complex [NiCI4]2- write (i) the IUPAC name (ii) The hybridisation type (iii) The shape of the complex

    1. Write a note on zeolites.

    2. Explain the oxidising property of sulphuric acid.

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