XII CHEMISTRY CBSE MODEL PAPER 2014
2 SAMPLE QUESTION PAPER [B]
CHEMISTRY (043)
CLASS- XII - (2013-14)
Time
Allowed: 3 Hrs
Maximum
Marks: 70
General Instructions:
All questions are compulsory.
1.
Question No. 1-8 are very short answer
questions and carry 1 mark each.
2.
Question No. 9-18 are short answer
questions and carries 2 marks each.
3.
Question No. 19-27 are also short answer
questions and carries 3 marks
each.
5. Question No. 28-30 are long answer
questions and carries 5 marks each.
6. Use log tables if necessary, use of
calculators is not allowed.
1. Write IUPAC
name of the compound- 1
(CH3)3C CH2 COOH
2. Why does PCl5
fume in moisture? 1
3. What happens
when D Glucose is treated with HNO3 1
(4) Give the IUPAC name of the organic compound 1
CH3 COCH2 CO CH3
(5)
Name the monomers of nylon 2 or nylon 6 ploymer. 1
(6) Give one example of an artificial sweetener used by the
diabetic patients. 1
(7) Direct nitration of aniline is not carried out. Explain why? 1
(8) What type of linkage holds together the monomers of D.N.A.? 1
(9) Differentiate between schottky and Frenkel defect. (2)
10. Analysis shows that a metal oxide has the empirical formula
M0.96 O1.00.
Calculate the percentage of M2+ and M3+
Ions in this crystal?
2
OR
In an ionic compound the anion (N¯)
form cubic close type of packing.
While the cation (M+)
ions occupy one third of the tetrahedral
voids. Deduce the empirical formula of the compound
[B]
and the
coordination number of (M+)
ions.
2
11. Explain the following-
2
(i)
Kolrausch ,s law
(ii)
Faraday first law of electrolysis
12. Write the chemical equations for all the steps involved in the
rusting of iron. Give any one method to
prevent rusting of iron. 2
13. A metal ion Mn+ having d4 valence
electronic configuration combines
with three didentate ligands to form a complex
Compound. Assuming
(i) Draw the diagram showing d orbital
splitting during this complex
formation.
(ii) write the electronic
configuration of the valence electrons of the
metal Mn+ ion in terms of t2g and
eg.
2
14. A mixed oxide of iron and chromium FeOCr2O3 is
fused with sodium carbonate in the
presence of air to form a yellow coloured compound
(A). On acidification the compound (A) forms an orange coloured compound (B), which is a strong oxidizing
agent. Identify
(i) The compounds
(A) and (B)
(ii) write balanced
chemical equation for each step 2
15. An optically active compound having molecular formula C7H15Br
reacts with aqueous KOH to give a racemic mixture of products. Write the
mechanism involved for this reaction. 2
[B]
16. Write the formula of main product formed in the following
chemical reactions.
(i) CH3Br + AgF-----------------
(ii) CH3CH2Br
+ Nal ---------
2
17. Differentiate the following pair of polymers based on the
property mentioned against each.
(i) Novolac and
Bakelite (structure)
(ii) Buna-s and
Terylene (intermolecular forces of attraction) 2
18. In order to wash clothes with water containing dissolved
calcium hydrogen carbonate, which cleaning agent will you prefer and why: soaps
or synthetic detergents? Give one advantage of soaps over synthetic detergents.
2
19. Heptane and octane form an ideal solution at 373 K, The vapour
pressures of the pure liquids at this temperature are 105.2 KPa and 46.8 KPa
respectively. If the solution contains 25g of heptane and 28.5g of octane,
calculate
(i) Vapour pressure
exerted by heptane
(ii) Vapour
pressure exerted by solution
(iii) Mole fraction
of octane in the vapour phase. 3
20. The following chemical reaction is occurring in an
electrochemical cell.
Mg(s) + 2 Ag+ (0.0001 M)
Mg2+ (0.10M) + 2 Ag(s)
The electrode
values are
Mg2+ / Mg = – 2. 36 V
Ag+ / Ag = 0.81 V
For this cell
calculate EMF of the cell.
21. Consider the adsorption isotherms given below and interpret
the variation in the extent of adsorption (x/m) when
(a) (i) temperature increases at constant
pressure
[B]
(ii) Pressure
increases at constant temperature
(b)
Name the
catalyst and the promoter used in Haber’s process for manufacture of
ammonia. 3
22. Account for the following facts
(a) The reduction
of a metal oxide is easier if the metal formed is in liquid state at the
temperature of reduction.
(b) The reduction
of Cr2O3 with Al is thermodynamically feasible, yet it
does not occur at room temperature.
(c) Pine oil is
used in froth floatation method. 3
23. Explain the
following facts
(a) Transition metals
act as catalysts.
(b) Chromium group
elements have the highest melting points in their respective series.
(c) transition
metals form coloured complexes. 3
24. (a) Give a chemical test to distinguish between the following
pairs of compounds.
(i)Phenol and
benzyl alcohol
(ii) Methyl amine
and ethyl amine.
(b) Why is phenol
more acidic than ethanol? 3
25. Account for the following observations
(i) Among the
halogens F2 is the strongest oxidizing agent?
(ii) Fluorine
exhibits only – 1 oxidation state whereas other halogens exhibit higher
positive oxidation states also.
(iii) Acidity of
oxo acid of chlorine is
HOCl < HOClO < HOClO2
< HOClO3 3
26. Give possible
explanation for each of the following.
(i) The presence of
a base is needed in the ammonolysis of alkyl halides.
(ii) Aromatic
primary amines cannot be prepared by Gabriel
[B]
Phthalimide
syntheses.
3
27. Explain the following
3
(i) Rimier tiemann reaction
(ii) Aldol reaction
OR
(i)Clemension reaction
(ii)HVZ reaction
28. (i) what is the order of the reactions?
(ii) What are the
units of rate constant k for Zero order?
(iii) Give the
relationship between k and t ½ (half life period) for Zero order reaction
(iv) Draw the slope
of the second order?
5
OR
For a certain chemical reaction
A + 2B 2C + D
The experimentally
obtained information is tabulated below.
Experiment
[A]0 [B]0 Initial rate
1. 0.30 0.30 0.096
2. 0.60 0.30 0.384
3. 0.30 0.60 0.192
4. 0.60 0.60 0.768
For this reaction
(i) Derive the order of reaction w.r.t. both
the reactants A and B.
(ii) Write the rate law.
(iii)
Calculate the value of rate constant k
(iv)
Write the expression for the rate of reaction in terms of A and
C. 5
29. A translucent white waxy solid (A) on heating in an inert
atmosphere is converted to its allotropic form (B).Allotrope (A) on reaction
with
[B]
very dilute aqueous
KOH liberates a highly poisonous gas (C) having rotten fish smell. With excess
of chlorine forms (D) which hydrolyses to compound (E). Identify compounds (A)
to (E). 5
OR
Complete the following reaction
(i)
2H3PO3-----heat---------
(ii)
P4 + NaOH --------
(iii)
C2H50H + K2Cr207
+H2SO4 ----------
30. (i) Rault law for non volatile solute.
(ii) Zone refining.
(iii)Shape selective catalysis
OR
An organic compound
(A) having molecular formula C9H10O forms an orange red
precipitate (B)
With 2, 4 – DNP reagent. Compound (A) gives a
yellow precipitate (C) when heated in the presence of iodine and NaOH along with
a colourless compound (D). (A) does not reduce Tollen’s reagent or Fehling’s
solution nor does it decolorize
Bromine water. On
drastic oxidation of (A) with chromic acid, a carboxylic acid (E) of molecular
formula C7H6O2 is formed. Deduce the
structures of the organic compounds (A) to (E). 5
*********** *************
BY DR SUDHIR TOMAR
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