Board Paper of Class 12-Science 2007 Chemistry (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
Find out
the number of atoms per unit cell in a face-centred cubic structure
having only single atoms at its lattice points.
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- Question 3
Express the rate of the following reaction in terms of disappearance
of hydrogen in the reaction.
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- Question 4
Name the
following compound according to IUPAC system:
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- Question 6
(a) Write the mathematical expression for the relationship of the wavelength (λ) of a moving particle and its momentum (P)
(b) What physical meaning is attributed to the square of the absolute value of wave function, ?
OR
State the Heisenberg Uncertainty Principle and explain as to why it is not of real consequence when applied to a macroscopic object, like a cricket ball.
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- Question 7
Define
Conductivity and molar conductivity for the solution of an
electrolyte.
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- Question 8
How would
you account for the following?
(i)
Sulphur hexafluoride is less reactive than sulphur tetrafluoride.
(ii) Of
the noble gases only xenon forms known chemical compounds.
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- Question 9
On
the basis of the standard electrode potential values stated for acid
solution, predict whether Ti4+
species may be used to oxidise FeII
to FeIII
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- Question 10
What are
chiral objects? Indicate the presence of centre of chirality, if any,
in the molecules of 3-bromopent-1-ene.
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- Question 11
How may
the following conversions be carried out?
(i)
Propene to propan-2-ol
(ii)
Anisole to phenol
(Write the
reaction only).
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- Question 12
Write
formulae of the monomers of polythene and Teflon.
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- Question 13
Define bond order in a diatomic molecule. Find the bond order in O2molecule. State and explain magnetic character of molecular oxygen.
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- Question 14
Assign
reasons for the following:
(i)
Phosphorus-doped silicon is a semiconductor.
(ii)
Schottky defect lowers the density of a solid.
(iii) Some
of the very old glass objects appear slightly milky instead of being
transparent.
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- Question 15
A
0.1539 molal aqueous solution of cane sugar (mol.
mass = 342 g mol−1)
has a freezing point of 271 K while the freezing point of pure water
is 273.15 K. What will be the freezing point of an aqueous solution
containing 5 g of glucose (mol. mass = 180 g mol−1)
per 100 g of solution?
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- Question 16
Calculate
the standard cell potential of the galvanic cell in which the
following reaction takes place:
Also
calculate the ΔrG
Θ
value of the reaction.
(Given
and
F = 96500 C mol−1)
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- Question 17
The
rate constant for a first-order reaction is
60 s−1.
How much time will it take to reduce the concentration of the
reactant to 1/10th
of its initial value?
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- Question 18
Describe
the following types of colloids, giving an example for each:
(i)
Multimolecular colloids
(ii)
Macromolecular colloids
OR
Explain
the following terms with a suitable example in each case:
(i)
Shape-selective catalysis
(ii)
Dialysis
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- Question 19
How would
you account for the following?
(i)
The transition elements have high enthalpies of atomisation.
(ii) The
transition metals and their compounds are found to be good catalysts
in many processes.
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- Question 20
Describe
for any two
of the following complex ions, the type of hybridisation, shape and
magnetic property:
(i)
(ii)
(iii)
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- Question 21
Complete
the following statements for nuclear reactions:
(i)
(ii)
(iii)
(Note: You
may use ‘X’ as symbol if the correct symbol in a reaction
is not known)
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- Question 22
Write one
chemical equation for each, to illustrate the following reactions:
(i)
Rosenmund reduction
(ii)
Cannizzaro reaction
(iii)
Fischer esterification
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- Question 23
Account
for any two
of the following
(a) Amines
are basic substances while amides are neutral.
(b) Nitro
compounds have higher boiling points than the hydrocarbons having
almost the same molecular mass.
(c)
Aromatic amines are weaker bases than aliphatic amines.
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- Question 24
(a)
Describe and illustrate with an example each, a mordant dye and a
detergent,
(b) Give
an example of a liquid propellant.
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- Question 25
(a) Prove that ΔGsystem= − TΔStotalfor a system which is not isolated.
(b) The decomposition of Fe2O3is a non-spontaneous process
Show that the reduction of Fe2O3by CO can be made spontaneous by coupling with the following reaction:
OR
(a) Define the following terms:
(i) Entropy
(ii) A spontaneous process
(b) Given below are the standard Gibbs energy changes for two reactions at 1773 K:
Discuss the possibility of reducing Al2O3with carbon at this temperature. Given that:
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- Question 26
(a) Assign
reasons for the following:
(i)
PbO2
is a stronger oxidising agent than SnO2
(ii)
In solid state PCl5
behaves as an ionic species,
(iii)
Aluminium chloride (AlCl3)
is very often used as a catalyst.
(b) What
is the structural difference between orthosilicates and
pyrosilicates?
OR
(a) Assign
reasons for the following:
(i) The
acid strengths of acids increase in the order
HF <
HCl < HBr < HI
(ii) The
lower oxidation state becomes more stable with increasing atomic
number in Group 13.
(iii)
H3PO2
behaves as a monoprotic acid.
(b) Draw
the structures of the following compounds:
(i)
SF4
(ii)
XeF2
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- Question 27
(a) Answer
the following question briefly:
(i) What
are reducing sugars?
(ii) What
is meant by denaturation of a protein?
(iii) How
is oxygen replenished in our atmosphere?
(b) Define
enzymes.
OR
(a) Answer
the following questions briefly:
(i) What
are any two good sources of vitamin A?
(ii) What
are nucleotides?
(iii) Give
an example of simple lipids.
(b) How
are carbohydrates classified?
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