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Board Paper of Class 12-Science 2022 Chemistry Term-II Delhi(Set 3) - Solutions

General Instructions:
Read the following instructions very carefully and strictly follow them:
1. This question paper contains 12 questions. All questions are compulsory.
2. This question paper comprises of three sections- Section
A, B and C.
3. Section A - Q. No. 1 to 3 are very short-answer type questions carrying 2 marks each.
4. Section
B - Q. No. 4 to 11 are short-answer type questions carrying 3 marks each.
5. Section C - Q. No. 12 is case based question carrying 5 marks.
6. Use of log tables and calculators is not allowed.

  • Question 1
    Explain the following reactions :
    (a) Wolff Kishner reduction
    (b) Cannizzaro reaction VIEW SOLUTION

  • Question 2
    Arrange the following in the increasing order of the property mentioned:
    (a) CH3COOH, ClCH2OOH, FCH2COOH (Acid strength)
    (b) CH3CHO, CH3CH2OH, CH3CH2CH3 (Boiling Points) VIEW SOLUTION

  • Question 3
    Answer the following questions (Do any two):
    (a) Identify the order of reaction from the following unit for its rate constant:
    (b) The conversion of molecules A to B follow second order kinetics. If concentration of A is increased to three times, how will it affect the rate of formation of B?
    (c) Write the expression of integrated rate equation for zero order reaction. VIEW SOLUTION

  • Question 4
    Account for the following:
    (i) pkb of aniline is more than that of methylamine.
    (ii) Aniline does not undergo Friedel-Crafts reaction.
    (iii) Primary amines have higher boiling points than tertiary amines.


    (i) Arrange the following compounds in the increasing order of their basic strength in aqueous solution:
    CHNH2, (CH3)3 N, (CH3)2 NH
    (ii) What is Hinsberg's reagent?
    (iii) What is the role of pyridine in the acylation reaction of amines? VIEW SOLUTION

  • Question 5
    (a) Write the IUPAC name of the following complex:
    (b) On the basis of crystal field theory, write the electronic configuration of d5 ion if ∆0 < P.
    (c) What are ambidentate ligands? VIEW SOLUTION

  • Question 6
    (a) Write any two consequences of Lanthanoid Contraction.
    (b) Name the element of 3d series which exhibits the largest number of oxidation states. Give reason. VIEW SOLUTION

  • Question 7
    Observe the graph shown in figure and answer the following questions :

    (a) What is the order of the reaction ?
    (b) What is the slope of the curve ?
    (c) Write the relationship between k and t12 (half life period) VIEW SOLUTION

  • Question 8
    Give reasons for the following statements:
    (a) Transition elements and their compounds act as good catalysts.

    (b) E°Mn2+/Mn value is highly negative as compared to other elements.

    (c) Cr2+ is a strong reducing agent. VIEW SOLUTION

  • Question 9
    (i) Define coagulation.
    (ii) State Hardy-Schulze rule.
    (iii) What is Electrophoresis?


    Write three differences between Physisorption and Chemisorption. VIEW SOLUTION

  • Question 10
    An aromatic compound 'A' (C7H6O2) on reaction with aqueous ammonia and heating forms compound 'B'. 'B' on heating with Br2 and alcoholic potash forms a compound 'C' of molecular formula C6H7N. Write the reactions involved and identify 'A', 'B', 'C'.


    A compound 'A' on reduction with iron scrap and hydrochloric acid gives compound 'B' with molecular formula C6H7N. Compound 'B' on reaction with CHCl3 and alcoholic KOH produces an obnoxious smell of carbylamine due to the formation of 'C'. Identify 'A, 'B' and 'C and wrtie the chemical reactions involved. VIEW SOLUTION

  • Question 11
    Complete the following:

    (i) CH3CN 2. H2O1. A1Hi-Bu2'A'H+H2N-OH'B'

    (ii) Write IUPAC name of the following compound:


    (iii) Write chemical test to distinguish between the following compounds:
    ​Phenol and Benzoic acid


    Convert the following:
    (i) Benzoic acid to Benzaldehyde
    (ii) Propan-1- ol to 2-Bromopropanoic acid
    (iii) Acetaldehyde to But-2-enal VIEW SOLUTION

  • Question 12
    Read the passage given below and answer the questions that follow:
    Oxidation-reduction reactions are commonly known as redox reactions. They involve transfer of electrons from one species to another. In a spontaneous reaction, energy is released which can be used to do useful work. The reaction is split into two half reactions. Two different containers are used and a wire is used to drive the electrons from one side to the other and a Voltaic/Galvanic cell is created. It is an electrochemical cell that uses spontaneous redox reactions to generate electricity. A salt bridge also connects to the half cells. The reading of the voltmeter gives the cell voltage or cell potential or electromotive force. If Ecello is positive the reaction is spontaneous and if it is negative the reaction is non-spontaneous and is referred to as electrolytic cell. Electrolysis refers to the decomposition of a substance by an electric current. One mole of electric charge when passed through a cell will discharge half a mole of a divalent metal ion such as Cu2+. This was first formulated by Faraday in the form of laws of electrolysis.

    The conductance of material is the property of materials due to which a material allows the flow of ions through itself and thus conducts electricity. Conductivity is represented by, k and it depends upon nature and concentration of electrolyte, temperature etc. A more common term molar conductivity of a solution at a given concentration is conductance of the volume of solution containing one mole of electrolyte kept between two electrodes with the unit area of cross-section and distance of unit length. Limiting molar conductivity of weak electrolytes cannot be obtained graphically.

    (a) Is silver plate the anode or cathode?
    (b) What will happen if the salt bridge is removed?
    (c)When does electro-chemical cell behaves like an electrolytic cel1?
    (d) (i) What will happen to the concentration of Zn2+ and Ag+ when Ecell = 0.
    (ii) Why does conductivity of a solution decreases with dilution?
    (d) The molar conductivity of a 1.5 M solution of an electrolyte is found to be 138.9 S cm2 mol–1. Calculate the conductivity of this solution. VIEW SOLUTION
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