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Board Paper of Class 12-Science 2014 Chemistry (SET 3) - Solutions

General Instructions:
(i) All questions are compulsory
(ii) Question numbers 1 to 8 are very short-answer questions and carry 1 mark each.
(iii) Question numbers 9 to 18 are short-answer questions and carry 2 marks each.
(iv) Question numbers 19 to 27 are also short-answer questions and carry 3 marks.
(v) Question numbers 28 to 30 are long-answer questions and carry 5 marks each.
(vi) Use Log Tables, if necessary. Use of calculators is not allowed.

  • Question 1

    What are the dispersed phase and dispersion medium in milk?


  • Question 2

    Name the method used for refining of copper metal.


  • Question 4
    The conversion of primary aromatic amines into diazonium salts is known as __________ . VIEW SOLUTION

  • Question 5

    Which of the following is a fibre?

    Nylon, neoprene, PVC


  • Question 6

    Write the products of the hydrolysis of lactose.


  • Question 7
    Identify the chiral molecule in the following pair:

  • Question 8

    Write the structure of 2-hydroxybenzoic acid.


  • Question 9

    Complete the following equations:

    (i) C + conc. H2SO4
    (ii) XeF2 + H2O →


  • Question 10

    Draw the structures of the following:

    (i) XeO3
    (ii) H2SO4


  • Question 11

    Write the names of monomers used for getting the following polymers:

    (i) Teflon
    (ii) Buna-N


  • Question 12
    An element with density 2.8 g cm−3 forms of f.c.c. unit cell with edge length 4 × 10−8 cm. Calculate the molar mass of the element.
    (Given: NA = 6.022 × 1023 mol​−1)

  • Question 13

    (a) Write the type of magnetism observed when the magnetic moments are aligned in parallel and anti-parallel directions in unequal numbers.

    (b) Which stoichiometric defect decreases the density of the crystal?


  • Question 14

    Define the following terms:

    (i) Molar conductivity (m)
    (ii) Secondary batteries


  • Question 15
    Write the mechanism of the following reaction:


  • Question 16

    For a chemical reaction R → P, the variation in the concentration (R) vs. time (t) plot is given as

    (i) Predict the order of the reaction.
    (ii) What is the slope of the curve?


  • Question 17

    Write the principle behind the froth floatation process. What is the role of collectors in this process?


  • Question 18
    Write the equations involved in the following reactions:

    (i) Reimer − Tiemann reaction
    (ii) Williamson synthesis

  • Question 19
    (i) Write the IUPAC name of the complex [Cr(NH3)4Cl2]Cl.
    (ii) What type of isomerism is exhibited by the complex [Co(en)3]3+?
                (en = ethane-1,2-diamine)
    (iii) Why is [NiCl4]2− paramagnetic but [Ni(CO)4] is diamagnetic?
            (At. nos. : Cr = 24, Co = 27, Ni = 28) VIEW SOLUTION

  • Question 20
    (a) Draw the structures of major monohalo products in each of the following reactions :

    (b) Which halogen compound in each of the following pairs will react faster in SN2 reaction:
    (i) CH3Br or CH3I
    (ii) (CH3)3C−Cl or CH3−Cl VIEW SOLUTION

  • Question 21

    Account for the following:
    (i) Primary amines (R-NH2) have higher boiling point than tertiary amines (R3N).
    (ii) Aniline does not undergo Friedel - Crafts reactions:
    (iii) (CH3)2NH is more basic than (CH3)3N in an aqueous solution.


    Give the structures of A, B and C in the following reactions:

    (i) C6H5NO2   Sn + HCl     A 273 K  NaNO2 + HCl    B    H2O   

    (ii) CH3CN H2O/H+ A     NH3     B    Br2+KOH   C


  • Question 22
    On the occasion of World Health Day, Dr. Satpal organized a 'health camp' for the poor farmers living in a nearby village. After check-up, he was shocked to see that most of the farmers suffered from cancer due to regular exposure to pesticides and many were diabetic. They distributed free medicines to them. Dr. Satpal immediately reported the matter to the National Human Rights Commission (NHRC). On the suggestions of NHRC, the government decided to provide medical care, financial assistance, setting up of super-speciality hospitals for treatment and prevention of the deadly disease in the affected villages all over India.
    (i) Write the values shown by
    (a) Dr. Satpal
    (b) NHRC
    (ii) What type of analgesics are chiefly used for the relief of pains of terminal cancer?
    (iii) Give an example of artificial sweetener that could have been recommended to diabetic patients. VIEW SOLUTION

  • Question 23
    Define the following terms:

    (i) Nucleotide
    (ii) Anomers
    (iii) Essential amino acids VIEW SOLUTION

  • Question 24
    (a) Calculate ∆rG° for the reaction
    Mg (s) + Cu2+ (aq) → Mg2+ (aq) + Cu (s)
    Given : E°cell = + 2·71 V, 1 F = 96500 C mol−1
    (b) Name the type of cell which was used in Apollo space programme for providing electrical power.

  • Question 25

    The following data were obtained during the first order thermal decomposition of SO2Cl2 at a constant volume :
    SO2Cl2 (g) → SO2 (g) + Cl2 (g)



    Total pressure/atm







    Calculate the rate constant.
    (Given : log 4 = 0·6021, log 2 = 0·3010)


  • Question 26
    What are emulsions? What are their different types? Give one example of each type. VIEW SOLUTION

  • Question 27
    Give reasons for the following:
    (i) (CH3)3P = O exists but (CH3)3N = O does not.
    (ii) Oxygen has less electron gain enthalpy with negative sign than sulphur.
    (iii) H3PO2 is a stronger reducing agent than H3PO3.

  • Question 28
    (a) Complete the following equations :
    (i)  Cr2O72- + 2OH- 
    (ii) MnO4- + 4H+ + 3e- 

    (b) Account for the following :
    (i) Zn is not considered as a transition element.
    (ii) Transition metals form a large number of complexes.
    (iii) The E° value for the Mn3+/Mn2+ couple is much more positive than that for Cr3+/Cr2+ couple.


    (i) With reference to structural variability and chemical reactivity, write the differences between lanthanoids and actinoids.
    (ii) Name a member of the lanthanoid series which is well known to exhibit +4 oxidation state.
    (iii) Complete the following equation :
    MnO4- + 8H+ + 5e-
    (iv) Out of Mn3+ and Cr3+, which is more paramagnetic and why?
    (Atomic nos. : Mn = 25, Cr = 24) VIEW SOLUTION

  • Question 29
     (a) Write the products formed when CH3CHO reacts with the following reagents:
         (i) HCN
         (ii) H2N−OH
         (iii) CH3CHO in the presence of dilute NaOH

    (b) Give simple chemical tests to distinguish between the following pairs of compounds:
         (i) Benzoic acid and Phenol
         (ii) Propanal and Propanone


    (a) Account for the following:
         (i) Cl−CH2COOH is a stronger acid than CH3COOH.
         (ii) Carboxylic acids do not give reactions of carbonyl group.

    (b) Write the chemical equations to illustrate the following name reactions:
         (i) Rosenmund reduction
         (ii) Cannizzaro's reaction

    (c) Out of CH3CH2−CO−CH2−CH3 and CH3CH2−CH2−CO−CH3, which gives iodoform test? VIEW SOLUTION

  • Question 30
    (a) Define the following terms :
    (i) Molarity
    (ii) Molal elevation constant (Kb)

    (b) A solution containing 15 g urea (molar mass = 60 g mol–1) per litre of solution in water has the same osmotic pressure (isotonic) as a solution of glucose (molar mass = 180 g mol–1) in water. Calculate the mass of glucose present in one litre of its solution.

    (a) What type of deviation is shown by a mixture of ethanol and acetone? Give reason.

    (b) A solution of glucose (molar mass = 180 g mol–1) in water is labelled as 10% (by mass). What would be the molality and molarity of the solution?
    (Density of solution = 1.2 g mL–1) VIEW SOLUTION
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