Select Board & Class

Login

Board Paper of Class 12-Science 2007 Chemistry Delhi(SET 1) - Solutions

General Instructions:
(i) All questions are compulsory.
(ii)  This question paper consists of four sections A, B, C and D. 
Section A contains 5 questions of one mark each.
Section B is of 7 questions of two marks each.
Section C is of 12 questions of three marks each and
Section D is of 3 questions of five marks each.
(iii) There is no overall choice. However, an internal choice has been provided.
(iv) Wherever necessary, the diagrams drawn should be neat and properly labelled.
  • Question 1

    What is the number of atoms per unit cell in a body-centred cubic structure?

    VIEW SOLUTION
  • Question 3

    For the reaction

    the rate law is expressed as

    rate = k[Cl2][NO]2

    What is the overall order of this reaction?

    VIEW SOLUTION
  • Question 5

    Why do nitro compounds have high boiling points in comparison with other compounds of same molecular mass?

    VIEW SOLUTION
  • Question 6

    State ‘Pauli’s exclusion principle’. Explain giving an example how this principle limits the maximum occupancy of an energy level in an atom.

    OR

    State ‘Aufbau principle’ and give the order in which the energies of orbitals increase and hence they are filled in that order.

    VIEW SOLUTION
  • Question 7

    A reaction with, always has an equilibrium constant value greater than 1. Why? 

    VIEW SOLUTION
  • Question 8

    Write balanced chemical equations for the following reactions:

    (i) Aluminium dissolves in aqueous hydrochloric acid

    (ii) Tin reacts with a hot alkali solution

    VIEW SOLUTION
  • Question 9

    Write the structures of the following species:

    (i) H3PO2 (ii) H2SO5

    VIEW SOLUTION
  • Question 10

    Identify whether the following pairs of compounds are structural or geometrical isomers:

    (i)

    (ii)

    VIEW SOLUTION
  • Question 11

    How would you account for the following:

    (i) Phenols are much more acidic than alcohols.

    (ii) The boiling points of ethers are much lower than those of the alcohols of comparable molar masses.

    VIEW SOLUTION
  • Question 12

    Draw the structure of the monomer of each of the following polymers:

    (i) Polyvinylchloride (PVC) (ii) Nylon-6

    VIEW SOLUTION
  • Question 13

    Write the molecular orbital configurations of the following species and rearrange them in the increasing order of their bond lengths:

    and O2.

    VIEW SOLUTION
  • Question 14

    Explain each of the following with a suitable example:

    (i) Paramagnetism

    (ii) Piezoelectric effect

    (iii) Frenkel defect in crystals

    VIEW SOLUTION
  • Question 15

    In the production of water gas the reaction involved is:

    C(s) + H2O(g) →CO(g) + H2(g), ΔrH°= +131.4 kJ mol−1

    For this reaction, ΔrS°is +134 JK−1mol−1. Find out the spontaneous feasibility of this reaction at (i) 25°C and (ii) 1000°C.

    VIEW SOLUTION
  • Question 16

    An antifreeze solution is prepared from 222.6 g of ethylene glycol [C2H4(OH)2] and 200 g of water. Calculate the molality of the solution. If the density of this solution be 1.072 g mL−1, what will be the molarity of the solution?

    VIEW SOLUTION
  • Question 17

    The decomposition of NH3 on platinum surface, is a zero order reaction with k = 2.5 × 10−4 M s−1. What are the rates of production of N2 and H2?

    VIEW SOLUTION
  • Question 18

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

    (i) Emulsification

    (ii) Homogeneous catalysis

    OR

    Define adsorption. Write any two features which distinguish physisorption from chemisorption.

    VIEW SOLUTION
  • Question 19

    How would you account for the following?

    (i) The lower oxidation state becomes more stable with increasing atomic number in Group 13.

    (ii) Hydrogen fluoride is much less volatile than hydrogen chloride.

    (iii) Interhalogen compounds are strong oxidising agents.

    VIEW SOLUTION
  • Question 20

    Write the name and draw the structure of each of the following complex compounds:

    (i) [Co(NH3)4 (H2O)2]Cl3

    (ii) [Pt(NH3)4] [NiCl4]

    VIEW SOLUTION
  • Question 21

    The net nuclear reaction of a radioactive decay series is written as:

    Write three pieces of information that you get from the above equation.

    VIEW SOLUTION
  • Question 22

    Give chemical tests to distinguish between the following pairs of compounds:

    (i) Propanal and propanone

    (ii) Methyl acetate and ethyl acetate

    (iii) Benzaldehyde and benzoic acid

    VIEW SOLUTION
  • Question 23

    How would you achieve the following conversions:

    (i) Nitrobenzene to aniline

    (ii) An alkyl halide to a quaternary ammonium salt

    (iii) Aniline to benzonitrile

    Write the chemical equation with reaction conditions in each case.

    VIEW SOLUTION
  • Question 24

    (i) Give an example of a hybrid propellant.

    (ii) What are acid dyes?

    (iii) Name a food preservative which is most commonly used by food producers.

    VIEW SOLUTION
  • Question 25

    (a) Describe the general trends in the following properties of the first series of the transition elements:

    (i) Stability of +2 oxidation state

    (ii) Formation of oxometal ions

    (b) Assign reason for each of the following:

    (i) Transition elements exhibit variable oxidation states

    (ii) Transition metal ions are usually coloured

    OR

    (a) Write the steps involved in the preparation of:

    (i) K2Cr2O7 from Na2CrO4

    (ii) KMnO4 from K2MnO4

    (iii) Calomel from corrosive sublimate

    (b) What is meant by lanthanoid contraction? What effect does it have on the chemistry of the elements which follow lanthanoids?

    VIEW SOLUTION
  • Question 26

    (a) Calculate the emf of the cell

    Mg(s) | Mg2+ (0.1M) || Cu2+ (1 × 10−3 M) | Cu (s)

    Given: E° Cu2+/Cu = +0.34V, E° Mg2+/Mg = −2.37 V

    (b) Explain with examples the terms weak and strong electrolytes.

    OR

    (a) The resistance of a conductivity cell containing 0.001 M KC1 solution at 298 K is 1500 Ω. What is the cell constant if the conductivity of 0.001 M KCl solution at 298 K is 0.146 × 10−3 S cm−1?

    (b) Predict the products of electrolysis in the following:

    A solution of H2SO4 with platinum electrodes.

    VIEW SOLUTION
  • Question 27

    (a) Name the three major classes of carbohydrates and give an example of each of these classes.

    (b) Answer the following:

    (i) What type of linkage is responsible for the primary structure of proteins?

    (ii) Name the location where protein synthesis occurs in our body.

    OR

    (a) How are lipids classified? Give an example of each class.

    (b) Explain the following terms:

    (i) Mutarotation

    (ii) Avitaminosis

    VIEW SOLUTION
What are you looking for?

Syllabus