Board Paper of Class 12-Science 2004 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 8 questions of one mark each.
Section B is of 10 questions of two marks each.
Section C is of 9 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
Mention
a large scale use of the phenomenon called ‘reverse osmosis’.
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- Question 3
Mention
two properties of acetonitrile because of which it acts as a good
solvent.
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- Question 4
What
are the types of lattice imperfections
found in crystals?
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- Question 6
Write
the chemical reaction to transform butanal
to butanoic acid.
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- Question 7
Name
the type of structure possessed by a unit
cell of CsCl.
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- Question 10
Distinguish
between reaction rate and reaction rate constant (specific reaction
rate) of a reaction.
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- Question 11
Write the
cell reactions which occur in lead storage battery (i) when the
battery is in use and (ii) when the battery is on charging.
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- Question 12
Give
chemical reaction in support of each of the following statements:
(i) The +1 oxidation
state gets stabilised progressively from Ga to Ti in Group 13.
(ii) All
the bonds in PCl5 molecule
are not equivalent.
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- Question 14
Write the
names of reagents and equations in the conversion of
(i) phenol
to salicyl aldehyde
(ii) anisole
to p-methoxyacetophenone
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- Question 15
Write
the modes of free-radical polymerisation of
an alkene.
OR
Differentiate
between addition and condensation polymers based on the mode of
polymerisation. Give one example of each type.
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- Question 16
Differentiate
between Lanthanides and Actinides series.
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- Question 17
Calculate
the density of silver which crystallises in
the face-centred cubic structure. The distance between the nearest
silver atoms in this structure is 287 pm.
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- Question 18
Two
elements A and B form compounds having formula AB2
and AB4.
When dissolved in 20 g of benzene (C6H6),
1 g of AB2
lowers the freezing point by 2.3 Kwhereas
1.0 g of AB4
lowers it by 1.3 K.
The molar depression constant for benzene is 5.1 Kkg mol−1.
Calculate atomic masses of A and B.
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- Question 20
Conductivity
of 0.00241 M acetic acid is 7.896 × 10−5
S cm−1.
Calculate its molar conductivity and if
for
acetic acid is 390.5 S cm2
mol−1,
what is its dissociation constant?
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- Question 21
A
reaction is first order in A and second
order in B.
(i) Write
differential rate equation.
(ii) How
is the rate affected if the concentration of B is tripled?
(iii) How
is the rate affected when the concentrations of both A and B are
doubled?
What is
the significance of rate constant in the rate expression?
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- Question 22
How
are the colloids classified on the basis of the nature of interaction
between dispersed phase and dispersion medium? Describe an important
characteristic of each class. Which of
these sols need stabilising agents for preservation?
Or
What are
detergents? Give their scheme of classification. Why are the
detergents preferred over soaps?
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- Question 23
Draw
a figure to show splitting of degenerate d
orbitals in an octahedral crystal field. How does the magnitude of Δ0
decide the actual configuration of d
orbitals in a complex entity?
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- Question 24
Explain
the following terms with suitable examples:
(i) Frenkel
defect
(ii) Interstitials
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- Question 25
Draw
the structures of monomers for the following polymers.
Also draw the structures of the polymers and uses of:
(i) Teflon
(ii) PMMA
(iii) Buna-S
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- Question 27
Write the IUPAC names of the following:
(i)
![](https://img-nm.mnimgs.com/img/study_content/paper/1/12/5/318/Chem_2004_XII_SET-1_delhi_richa_LVN_html_m58878a06.jpg)
(ii) ![](https://img-nm.mnimgs.com/img/study_content/paper/1/12/5/318/Chem_2004_XII_SET-1_delhi_richa_LVN_html_m6d691b90.gif)
(iii)
![](https://img-nm.mnimgs.com/img/study_content/paper/1/12/5/318/Chem_2004_XII_SET-1_delhi_richa_LVN_html_7c44bffa.jpg)
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- Question 28
(a) Assign appropriate reason for each of the
following observations:
(i) Anhydrous
AlCl3
is used as a catalyst.
(ii) Phosphinic
acid behaves as a monoprotic acid.
(iii) SF6
is not easily hydrolysed whereas SF4
is readily hydrolysed.
(iv) No
form of elemental silicon is comparable to graphite.
(b) Draw
the structure of XeOF4 or
BrF3.
Or
Account
for the following:
(i) Ammonia
is a stronger base than phosphine
(ii) The tendency to exhibit +2 oxidation state increases with
increasing atomic number in group 14.
(iii) HF is a weaker acid than HI.
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- Question 29
(a) How
would you account for the following:
(i) The
transition elements exhibit high enthalpies of atomisation.
(ii) The 4d
and 5d
series of the transition metals have more frequent metal−metal
bonding in their compounds than do the 3d
metals.
(iii) There is a greater range of oxidation states
among the actinoids than among the lanthanoids.
(b) Write
the complete chemical equation for each of the following:
(i) An
alkaline solution of KMnO4
reacts with an iodide.
(ii) An
excess of SnCl2
solution is added to a solution of mercury (II)
Or
An aqueous
solution freezes at 272.4 K, while pure water freezes at 273.0 K.
Determine
(i) the
molality of the solution
(ii) the
boiling point of the solution
(iii) the
lowering of vapour pressure of water at 298 K
[Given
Kf
= 1.86 K kg mol−1,
Kb= 0.512 K kg mol−1
and vapour pressure of water at 298 K = 23.756 mm Hg]
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- Question 30
Name
the products obtained on complete
hydrolysis of DNA. Enumerate the structural differences between DNA
and RNA. In what way is a nucleotide different from a nucleoside?
Illustrate with examples.
Or
Define and
classify vitamins. Name the diseases caused due to lack of any three
of them.
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