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CBSE Class 12 Chemistry Practice Paper 2017: Set ‒ III

Feb 8, 2017 16:00 IST

    Download CBSE class 12th Chemistry practice paper 2017 for the coming CBSE board exams 2017.

    This practice paper is based on latest CBSE examination pattern of class 12th Chemistry. All the questions of this practice paper are from latest CBSE syllabus.

    CBSE board exams 2017 are about to start from 9th March 2017 and CBSE class 12th Chemistry board exam 2017 is scheduled to be held on 25th March 2017.

    In order to score maximum marks in CBSE board examination 2017, students should start solving previous year papers along with practice papers.

    In this article, we have provided a practice paper for CBSE class 12th Chemistry based on latest examination pattern. Most of the questions of this practice paper are based on important concepts of NCERT textbooks and previous year papers. These questions are very important for coming class 12th Chemistry board exam 2017. Students should try to solve this paper in less than 3 hours as this will enhance their writing speed.

    CBSE Class 12th Chemistry Syllabus 2017

    The complete practice paper is given below

    Time allowed: 3 hours                                                                                 Maximum Marks: 70

    General Instructions:

    • All questions are compulsory.

    • Questions number 1 to 5 are very short answer questions & carry 1 mark each.

    • Questions number 6 to 10 are very short answer question & carry 2 marks each.

    • Questions number 11 to 22 are also short answer question & carry 3 marks each.

    • Question number 23 is a value based question & carry 4 marks.

    • Questions number 24 to 26 are long answer question & carry 5 marks each.

    • Use log tables, if necessary.

    • Use of calculators is not allowed.

    1. What is the role of a depressant in Froth Floatation process for the concentration of a sulphide ore?

    2. Arrange the following compounds in correct order of reactivity in SN1 reaction

    CH3CH2CH2CH2Br, CH3CH2CH (Br) CH3, (CH3)2CHCH2Br , (CH3)3CBr

    3. Write IUPAC name of the given compound:

    CBSE Class 12 Practice Paper 2017, Question based on IUPAC

    4. Define Kraft temperature

    CBSE Class 12th Maths Practice Paper 2017

    5. Why does bleeding stop by rubbing alum?

    6. CuSO4. 5H2O is blue in colour while CuSO4 is colourless. Give reason?

    7. Write the Nernst equation for the cell reaction in the Daniel cell. How will the Ecell be affected when concentration of Zn2+ ions is increased?

    8. Give reason for the following observation:

    (i) The electron gain enthalpy with negative sign for fluorine is less than that of chlorine, still fluorine is a stronger oxidizing agent than chlorine.

    (ii) XeF2 is linear molecule without a bend.

    9. (i) Why salt bridge is essential in a galvanic cell?

    (ii) What is the role of ZnCl2 in a dry cell?

    10. The decomposition of NH3 gas on platinum surface has a rate constant of 2.5 × 10‒4 mol L‒1 s‒1. Find the order of reaction.

    OR

    10. Give an example of a reaction in which molecularly and order of a reaction are equal.

    11. (a) Why most of the transition metals do not displace hydrogen from dilute acids?

    (b) The transition elements have great tendency for complex formation.

    (c) Lanthanum and Lutetium do not show colouration in solutions. (At. No.: La = 57, Lu = 71)

    12. What is the difference between antiseptic and disinfectant?

    OR

    12. What are biodegradable and non-biodegradable detergents?

    CBSE Class 12 Chemistry Solved Practice Paper 2017: Set ‒ II

    13. A sample of ferrous oxide has actual formula Fe 0.931.00. In this sample, what fraction of metal ions are Fe2+ions? What type of non-stoichiometric defect is present in this sample?

    14. (a) What is the effect of temperature on chemisorptions?

    (b) How does the Brownian movement provide stability to the colloidal solution.

    (c) Lyophilic colloid is more stable than lyophobic colloid. Why?

    15. The thermal decomposition of HCO2H is a first order reaction with a rate constant of 2.4 × 10–3 s–1 at a certain temperature. Find how long will it take for three-fourths of initial quantity of HCO2H to decompose. (log 0.25 = – 0.6021)

    16. Write the name of the reagent used in the following conversions:

    (i) Phenol to 2, 4, 6-tribromophenol

    (ii) Butan-2-one to butan-2-ol

    (iii) Phenol to 2, 4, 6-tribromophenol

    CBSE Class 12 Chemistry 2017 Sample Paper

    17. (a) What is the role of cryolite in the metallurgy of aluminium?

    (b) What is the role of depressant in froth flotation process?

    18. A copper-silver cell is set up. The copper ion concentration is 0.10 M. The concentration of silver ion is not known. The cell potential when measured was 0.422 V. Determine the concentration of silver ions in the cell.

    (Given, EoAg+/Ag = +0.80 V, EoCu2+/Cu = 0.34 V)

    19. (i) Why we should take vitamin C regularly in our diet?

    (ii) What is invert sugar?

    (iii) Explain the meaning of peptide bond.

    20. Explain the following terms giving a suitable example in each case:

    (i) Ambident ligand

    (ii) Denticity of ligand

    (iii) Crystal field splitting in an octahedral field

    21. How would you obtain the following:

    (i) Benzoquinone from phenol

    (ii) 2-Methylpropan-2-ol from methylmagnesium bromide

    (iii) Propan-2-ol from propane

    22. (a) Classify the following as condensation and addition polymer?

    Bakelite, Terylene, Polyviyl chloride, Polythene

    (b) What is free radical addition polymerization?

    (c) Write basic difference between Buna – N and Buna – S.

    23. Himanshu’s brother likes taking medicines. He sometimes takes cough syrups even when he is not ill. One day, he took cough syrup when he was healthy. After some time he started feeling nausea, headache and his body started itching. Himanshu’s father did not take him to the doctor and wanted to give medicine on his own. Himanshu insisted that his father should not give medicine to his brother on his own but should take him to a doctor.

    After reading the above passage, answer the following questions:

    (i) Mention the values shown by Himanshu.

    (ii) Why did Himanshu’s brother body start itching and what kind of medicine will doctor prescribe him?

    (iii) Explain why medicines should not be taken without consulting doctor.

    (iv) Give one point of difference between agonist and antagonist.

    24. (a) Define the following terms:

    (i) Mole fraction

    (ii) Van’t Hoff factor

    (b) 100 mg of a protein is dissolved in enough water to make 100 mL of a solution. If this solution has an osmotic pressure 13.3 mm Hg at 25° C, what is the molar mass of protein? (R = 0.0821 L atm mol–1 K–1 and 760 mm Hg = 1 atm.)

    OR

    24. What is meant by:

    (i) Colligative properties

    (ii) Molality of a solution.

    (b) What concentration of nitrogen should be present in a glass of water at room temperature?

    Assume a temperature of 25° C, total pressure of 1 atmosphere and mole fraction of nitrogen in air of 0.78. [KH for nitrogen = 8.42 × 10–7 M/mm Hg]

    25. (a) Explain the mechanism of a nucleophilic attack on the carbonyl group of an aldehyde or a ketone.

    (b) An organic compound (A) (molecular formula C8H16O2) was hydrolysed with dilute sulphuric acid to give a carboxylic acid (B) and an alcohol (C). Oxidation of (C) with chromic acid also produced (B). On dehydration (C) gives but-1-ene. Write the equations for the reactions involved.

    OR

    25. (a) Give chemical tests to distinguish between the following pairs of compounds:

    (i) Ethanal and propanal

    (ii) Phenol and Benzoic acid

    (b) How will you bring about the following conversions?

    (i) Benzoic acid to benzaldehyde

    (ii) Ethanal to but-2-enal

    (iii) Propanone to propene

    Give complete reaction in each case.

    26. (a) What may be the possible oxidation states of the transition metals with the following d electronic configurations in the ground state of their atoms: 3d3 4s2, 3d5 4s2 and 3d6 4s2. Indicate relative stability of oxidation states in each case.

    (b) Write steps involved in the preparation of (i) Na2CrO4 from chromite ore and (ii) K2MnO4 from pyrolusite ore

    OR

    26. Give reasons for the following:

    (i) The enthalpies of atomisation of transition elements are high.

    (ii) The transition metals and many of their compounds act as good catalysts.

    (iii) From element to element the actinoid contraction is greater than the lanthanoid contraction.

    (iv) The E° value for the Mn3+ / Mn2+ couple is much more positive than that of Cr3+ / Cr2+.

    (v) Scandium (Z = 21) does not exhibit variable oxidation states and yet it is regarded as a transition element.

    Download this practice paper in PDF format

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