SARASWATI CHEMISTRY POINT
[C.B.SE. CLASS - XII]
CHEMISTRY (THEORY) – 2012
(SET-I, OUTSIDE DELHI)
Time Allowed: 3 hrs
M.M. : 70
General Instruction:
(i)
(ii)
(iii)
(iv)
(v)
(vi)
(vii)
All questions are compulsory
Marks for each question are indicated against it.
Question numbers 1 to 8 are very short answer questions and carry 1 marks each.
Question numbers 9 to 18 are short answer questions and carry 2 marks each.
Question numbers 19 to 27 are also short answer questions and carry 3 marks each.
Question numbers 28 to 30 are long answer questions and carry 5 mark each.
Use log tables if necessary. Use of calculators is not allowed.
Q: 1. How may the conductivity of the
intrinsic semiconductor be increased?
Q: 2. Define ‘peptization’.
Q: 3. How is copper extracted form a low
grade ore of it?
Q: 4. Which is a stronger reducing agent,
SbH3 of BiH3, and why?
Q: 5. What happens when bromine attacks
CH2 = CH – CH2 – C = CH?
Q: 6. Give IUPAC name:
O
CH3 – CH2 – CH = CH – C – H
Q: 7. Write the structure of the product
obtained when glucose is oxidized
with nitric acid.
Q: 8. Differentiate between disinfectants
and antiseptics.
Q: 9. Express the relation among cell
constant resistance of the solution in
the cell & conductivity of the solution.
PITAM PURA & ROHINI
SUDHIR PANWAR
How is molar conductivity of a
solution related to its conductivity?
Or
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.
Q: 10. A reaction is of second order with
respect to a reactant. How is its rate
affected if the concentration of the
reactant is (i) doubled (ii) reduced to
half?
Q: 11. Which methods are usually employed
for purifying the following metals:
(i) Nickel
(ii) Germanium
Q: 12. Explain the following facts giving
appropriate reason in each case:
(i) NF3 is an exothermic compound
whereas NCl3 is not.
(ii) All the bonds is SF4 are not
equivalent.
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SARASWATI CHEMISTRY POINT
Q: 13. Complete the following chemical
reaction equations:
(i) Cr2O72- + I ¯ + H+ →
(ii) MnO¯4 + NO¯2 + H+ →
Q: 14. Explain the mechanism of acid
catalysed hydration of an alkene to
form corresponding alcohol.
Q: 15. Explain the following behaviours:
(i) Alcohols are more soluble in
water than the hydrocarbons of
comparable molecular masses.
(ii) Ortho-nitrophenol is more acidic
than ortho-methoxyphenol.
Q: 16. Describe the following giving the
relevant chemical equation in each
case:
(i) Carbylamine reaction
(ii) Hofmann’s bromamide reaction
Q: 17. Complete the following reaction
equations:
(i) C6H5N2Cl + H3PO2 + H2O →
(ii) C6H5NH2 + Br2 (aq.) →
Q: 18. What are food preservatives? Name
two such substances.
Q: 19. Copper crystallizes with face centred
cubic unit cell. If the radius of copper
atom is 127.8 pm, calculate the
density of copper metal. (Atomic
mass of Cu = 63.55 u and
Avogadro’s number NA = 6.02 × 1023
mol-1)
Or
Iron has a body centred cubic unit
cell with the cell dimension of
286.65 pm. Density of iron is 7.87 g
PITAM PURA & ROHINI
SUDHIR PANWAR
cm-3. Use this information to
calculate Avogadro’s number.
(Atomic mass of Fe = 56.0 u)
Q: 20. The electrical resistance of a column
of 0.05 M, NaOH solution of
diameter 1 cm and length 50 cm is
5.55 × 103 ohm.
Calculate it resistivity, conductivity
and molar conductivity.
Q: 21. The reaction, N2(g) + O2 (g) ⇌ 2
NO(g) contributes to air pollution
whenever a fuel is burnt in air at a
high temperature. At 1500 K,
equilibrium constant K for its is 1.0 ×
10-5. Suppose in a case [N2] = 0.80
mol L-1 and |O2| = 0.20 mol L-1
before any reaction occurs. Calculate
the equilibrium concentration of the
reactants and the product after the
mixture has been heated to 1500 K.
Q: 22. Explain the following terms giving a
suitable example for each:
(i)
Aerosol
(ii) Emulsion
(iii) Micelle
Q: 23. How would you account for the
following:
(i) Among Lanthanoids, Ln(III)
compounds are predominant,
However, occasionally in
solutions or in solid compounds,
+2 and +4 ions are also obtained.
(ii) The E° M2+/M for copper is positive
(0.34 V). Copper is the only
metal in the first series of
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SARASWATI CHEMISTRY POINT
transition elements showing this
behaviour.
(iii) The metallic radii of the third (5d)
series of transition metals are
nearly the same as those of the
corresponding members of the
second series.
Q: 24. Name the following coordination
entities and draw the structures of
their stereoisomers:
(i) [Co(en)2 Cl2]+ (en = ethan-1,2diamine)
(ii) [Cr(C2O4)3]3(iii) [Co(NH3)3 Cl3] (atomic numbers
Cr = 24, Co = 27)
Q: 25. Answer the following questions:
(i) What is meant by chirality of a
compound? Give an example.
(ii) Which one of the following
compounds is more easily
hydrolyzed by KOH and why?
CH3CHCICH2CH3 or
CH3CH2CH2Cl
(iii) Which one undergoes SN2
substitution reaction faster and
why?
I Or
Cl
Q: 26. What is essentially the difference
between α-glucose and β-glucose?
What is meant by pyranose structure
of glucose?
Q: 27. Differentiate between thermoplastic
and thermosetting polymers. Give
one example of each.
PITAM PURA & ROHINI
SUDHIR PANWAR
Q: 28. (a) Define the following terms:
(i) Mole fraction
(ii) Ideal solution
(b) 15.0 g of an unknown molecular
material is dissolved in 450 g of
water. The resulting solution
freezes at – 0.34° C. What is the
molar mass of the material? (Kf
for water = 1.86 K kg mol-1).
Or
(a) Explain the following:
(i) Henry’s law about dissolution
of a gas in a liquid.
(ii) Boiling point elevation
constant for a solvent
(b) A solution of glycerol in water
was prepared by dissolving some
glycerol in 500 g of water. This
solution has a boiling point of
100.42°C. What mass of glycerol
was dissolved to make this
solution? (Kb for water = 0.512 K
kg mol-1)
Q: 29. (a) Draw the molecular structures of
the following compounds:
(i) N2O5
(ii) XeOF4
(b) Explain the following
observations:
(i) Sulphur has a greater
tendency for catenation then
oxygen.
(ii) ICI is more reactive than I2.
(iii) Despite lower value of its
electron gain enthalpy with
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SARASWATI CHEMISTRY POINT
negative sing, fluorine (F2) is a
stronger oxidizing agent than Cl2.
Or
(a) Complete the following chemical
equations:
(i) Cu + HNO3 (dilute) →
(ii) XeF4 + O2F2 →
(b) Explain the following
observations:
(i) Phosphorus has greater
tendency for catenation than
nitrogen.
(ii) Oxygen is a gas but sulphur a
solid.
(iii) The halogens are coloured.
Why?
Q: 30. (a) Write a suitable chemical
equation to complete each o the
following transformations?
(b) An organic compound with
molecular formula C9H10O forms
2,4-DNP derivative, reduces
Tollen’s reagent and undergoes
Cannizzaro’s reaction. On
PITAM PURA & ROHINI
SUDHIR PANWAR
vigorous oxidation it gives 1, 2Benzenedicarboxylic acid,
Identify the compound.
Or
(a) Give chemical tests to distinguish
between
(i) Propanol an dpropanone
(ii) Benzaldehyde and
acetophenone
(b) Arrange the following compounds
in an increasing order of their
property as indicated:
(i) Acetaldehyde, Acetone,
Methyl tert-butyl ketone
(reactivity towards HCN)
(ii) Benzoic acid, 3-4Dinitrobenzoic acid, 4Methoxybenzoic and (acid
strength)
(iii) CH3CH2CH(Br) COOH,
CH3CH(Br) CH2COOH,
(CH3)2CH COOH (acid
strength)
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(4)
SARASWATI CHEMISTRY POINT
[C.B.SE. CLASS - XII]
CHEMISTRY (THEORY) – 2012
(SET-II, OUTSIDE DELHI)
Time Allowed: 3 hrs
M.M. : 70
General Instruction:
(i) All questions are compulsory
(ii) Marks for each question are indicated against it.
(iii) Question numbers 1 to 8 are very short answer questions and carry 1 marks each.
(iv) Question numbers 9 to 18 are short answer questions and carry 2 marks each.
(v) Question numbers 19 to 27 are also short answer questions and carry 3 marks each.
(vi) Question numbers 28 to 30 are long answer questions and carry 5 mark each.
(vii) Use log tables if necessary. Use of calculators is not allowed.
Note: Except for the following questions, all the remaining questions have been asked in Set-I.
Q: 1. Which stoichiometric defect increases
the density of a solid?
Q: 2. What is meant by ‘shape selective
catalysis?
Q: 3. What is the role of collectors in Froth
floatation process?
Q: 6. Write the IUPAC name of PH – CH =
CH – CHO.
Q: 17. Explain the cleaning action of soap.
Why do soaps not work in hard water?
Q: 20. A Voltaic cell is set up at 25°C with
the following half cells:
Al/Al3+ (0.001 M) and Ni/Ni2+ (0.50
M) Write an equation for the reaction
that occure when the cell generates an
electric current and determine the cell
potential.
E°Ni2+/Ni = - 0.25 V and E°Al3+/Al = 1.66 V (Log 8 × 10-6 = - 0.54)
Q: 23. Explain the following observations:
(i)Many of the transition elements are
known to form interstitial compounds.
PITAM PURA & ROHINI
SUDHIR PANWAR
(ii) There is a general increase in
density from titanium (Z = 22) to
copper (Z = 29).
(iii) The members of the actinoids
series exhibit a larger number of
oxidation states than the
corresponding members of the
lanthanoid series.
Q: 27. Explain the following terms giving a
suitable example for each:
(i) Elastomers
(ii) Condensation polymers
(iii) Addition polymers
Q: 30. (a) Draw the structures of the
following molecules:
(i) H3PO2
(ii) CIF3
(b) Explain the following
observations:
(i) Nitrogen is much less reactive
than phosphorus.
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SARASWATI CHEMISTRY POINT
(ii) Despite having greater polarity,
hydrogen fluoride boils at a lower
temperature than water.
(iii) Sulphur has greater tendency for
catenation than oxygen in the same
group.
Or
(a) Draw the structures of the following
molecules:
PITAM PURA & ROHINI
SUDHIR PANWAR
(i) N2O5
(ii) HCIO4
(b) Explain the following observation
(i) Fluorine does not exhibit any
positive oxidation state.
(ii) Helium forms no real chemical
compound.
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(6)
SARASWATI CHEMISTRY POINT
[C.B.SE. CLASS - XII]
CHEMISTRY (THEORY) – 2012
(SET-III, OUTSIDE DELHI)
Time Allowed: 3 hrs
M.M. : 70
General Instruction:
(i) All questions are compulsory
(ii) Marks for each question are indicated against it.
(iii) Question numbers 1 to 8 are very short answer questions and carry 1 marks each.
(iv) Question numbers 9 to 18 are short answer questions and carry 2 marks each.
(v) Question numbers 19 to 27 are also short answer questions and carry 3 marks each.
(vi) Question numbers 28 to 30 are long answer questions and carry 5 mark each.
(vii) Use log tables if necessary. Use of calculators is not allowed.
Note: Except for the following questions, all the remaining questions have been asked in Set-I & Set-II.
Q: 1. What are n-type semiconductors?
Q: 4. What is the basicity of H3PO2 acid and
why?
Q: 5. Write the IUPAC name of the
following:
H
CH3
H
H
Br
H
Q: 7. Write a reaction which shows that all
the carbon atoms in glucose are linked
in straight chain.
Q: 8. What is the cause of a feeling of
depression in human beings? Name a
drug which can be useful in treating
this depression.
Q: 10. Express the relation among cell
constant, resistance of the solution in
the cell and conductivity of the
solution. How is molar conductivity of
a solution related to its conductivity?
PITAM PURA & ROHINI
SUDHIR PANWAR
Or
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.
Q: 11. Explain the role of each of the
following:
(i) NaCN in the extraction of silver
(ii) SiO2 in the extraction of copper
Q: 18. Differentiate between disinfectants
and antiseptics. Give one example of
each group.
Q: 21. The electrical resistance of a column
of 0.05 M NaOH solution of
diameter 1 cm and length 50 cm is
5.55 / 103 ohm.
Calculate its resistivity, conductivity
and molar conductivity.
Q: 22. Write three distinct features of
chemisorptions which are not found
in physisorptions.
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SARASWATI CHEMISTRY POINT
Q: 23. Explain each of the following
observations:
(i) With the same d-orbital
configuration (d4), Cr2+ is a
reducing agent while Mn3+ is an
oxidizing agent.
(ii) Actinoids exhibit a much larger
number of oxidation states than
the lanthanoids.
(iii) There is hardly any increase in
atomic size with increasing
atomic numbers in a series of
transition metals.
PITAM PURA & ROHINI
SUDHIR PANWAR
Q: 24. Name of following coordination
entities and describe their
structures:
(i) [Fe(CN6)]4(ii) [Cr(NH3)4Ci2]+
(iii) [Ni(CN)4]2[Atomic numbers Fe = 26, Cr = 24,
Ni = 28]
Q: 26. Define the following as related to
proteins:
(i) Peptide linkage
(ii) Primary structure
(iii) Denaturation
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