2014 XII CBSE MODEL QUESTION PAPER OLD PATTERN
[B]
CHEMISTRY (043)
CLASS- XII - (2013-14)
: Time Allowed: 3 Hrs Maximum Marks 70
General Instructions:
1. All questions
are compulsory.
2. Question No.
1-8 are very short answer questions and carry 1 mark each.
3. Question No.
9-18 are short answer questions and carry 2 marks each.
4. Question No.
19-27 are also short answer questions and carry 3 marks each.
5. Question No.
28-30 are long answer questions and carry 5 marks each.
6. Use log
tables if necessary, use of calculators is not allowed.
1) Why is ferric chloride preferred over potassium chloride in
case of a
Cut leading to Bleeding? 1
(2)
Why does a tetrahedral complex of the type [MA2 B2] not show
geometrical isomerism? 1
(3) How do you account for the miscibility of ethoxyethane with
water?
1
4. A hydroxide ion
is a weaker base than an alkoxide ion. Justify. 1
5. Gelatin which
is a peptide is added in ice creams. What can be its role? 1
6. Write the
formula for the coordination compound
Tetra amminediaquacobalt(III)
Chloride.
1
7. On passing H2S
through an aqueous solution of SO2 a yellow turbidity
is formed. Why? 1
8. Why is red
phosphorous less reactive than white phosphorus. 1
9. A reaction is
second order with respect to a reactant. How is the rate of
the
Reaction
affected if the concentration of the reactant is
i) Doubled
ii) Reduced to ½ 2
OR,
A first order reaction is 15% complete
in 20 minutes. How long it take to
be 60%
Complete.
10. (a) What is the relationship between standard
free energy change and equilibrium Constant? 2
(b) The standard EMF of the cell
Zn(s) + Cu2+ (aq) ¾¾® ¾¾®
Zn2+(aq)
+ Cu (s) is 1.10v.
Calculate the standard free energy
change.
11.
Explain how (Pt
Cl2 (NH3)2) and (Pt (NH3)6] Cl4 differ in their electric
conductances. 2
12. Do the
following conversions. 2
(i) Benzyl alcohol to 2 phenyl
ethanoic Acid
(ii) Ethyl Chloride to propanoic Acid
13. Calculate the
packing efficiency in bcc structure. 2
14.
Determine the
type of cubic lattice to which a given crystal belongs if it has
edge Length of 290 pm and density is 7.80 g cm-3 (molecular
mass= 56 g mol-1). 2
15. How will you
distinguish between the following pairs of compounds? 2
(i) C2H5Br and C2H5Cl
(ii) Phenol and chlorobenzene
16. Write the
following name reaction. 2
(i) Sandmayer reaction
(ii) Gabriel's Phthalimide synthesis.
17. The
decomposition of NH3 on platinum surface is zero order reaction. What are The rates of production of N2 and H2
if K = 2.5×10-4
mol-1LS-1 2
18. Give reasons
for the following:- 2
(i) Ethylamine is soluble in water
whereas. Aniline is insoluble in water.
(ii) Primary amines have higher boiling
points than tertiary amines.
19. Write balanced
chemical equations for the following reactions. 3
(i) XeF6 undergoes
hydrolysis.
(ii)
Phosphorus is treated with concentrated nitric acid.
(iii) Orthophosphorous acid is heated.
20. Account for the
following 3
(i) A delta is formed at the point
where the river water enters the sea.
(ii)
Direct current is passed through a colloidal solution.
(iii) Ferric hydroxide sol is positively
charged.
21. Santosh
and
his mother went to a shop to purchase a battery for their inverter.
Shop keeper showed them two types of batteries one with Cadmium
plates and other with
lead plates. The battery with cadmium
plates was more expensive than the lead battery. Santosh's mother
wanted to purchase lead battery as it was cheaper.
After
reading above passage answer the following questions. 3
[B]
(a) As a student’s of chemistry, why would
you suggest to Santosh’s mother to
Buy the expensive cadmium plate battery. Give
two reasons.
(b) What are the values associated with the above decision.
22. (a) Copper can
be extracted by hydro metallurgy but not zinc. Explain.
(b) What is the role of cryolite in the
metallurgy of aluminum? 3
OR
(a) What is the role of depressant in froth
floatation process?
(b) Describe a method or refining of
nickel.
23. (a) Name one
substance which can act as both 3
(i) Analgesic and antipyretic
(ii) Antiseptic and disinfectant
(b) Write the composition of Dettol.
24. Write the mechanism for preparation of
diethyl ether from ethanol. 3
25. (i) Draw the structure of phosphinic acid
(H3PO2). 3
(ii)
Write a chemical reaction for its use as reducing agent.
(iii) Suggest a quantitative method for
estimation of the gas which protect
us from
UV rays of the sun.
26. (a) Differentiate between Keratin and
insulin. 3
(ii) Give one example each for essential and
non essential amino acids.
(iii) Give one reaction of D Glucose
which cannot be explained by its
open chiral Structure.
27. (a) Write the structures of the monomers
of Dacron. 3
(b) Give one example of a synthetic
rubber.
(c) Arrange the following polymers
in the increasing order of tensile strength
Nylon 6, Buna – S, Polythene.
28. Account for the
following. 5
(a) Silver is a transition metal but zinc is
not.
(b) The transition metals form a large number
of complex compounds.
(c)
MnO is basic white Mn2O7 is acidic in nature.
(d) Actinides show more number of
oxidation states than lanthanides.
[B]
(e)
Transition metals have high enthalpies of atomization.
OR
(I)
write chemical equations for the following reactions.
(a) Disproportionation of manganese (VI)
in acidic solution.
(b)
Acidification of potassium chromate solutions.
(c) Oxidation of nitrite ion by MnO4
- in acidic medium.
(II) (i)
Which is stronger reducing agent Cr2+ or Fe2+ and why.
(ii) Explain why Cu+ ion is not stable in
aqueous solution.
29. (a) State Henry's law and mention its two
applications. 5
(b) Which
of the following has higher boiling point and why. 0.1M NaCl or 0.1 M Glucose
(c) On dissolving 19.5 g of CH2FCOOH
in 500 g of water a depression of 10C in
Freezing point of water is observed.
Calculate the Vant Hoff factor.
Given Kf =
1.86
K Kg mol-1.
OR
(a) State Raoult's law for the
solutions containing nonvolatile solute.
Give its Mathematical expression also.
(b) A
solution containing 0.5 g of KCl dissolved in 100 gm of water freezes at -0.240C. Calculate the degree of
dissociation of the salt (K for water = 1.860C).
30. (a) Describe the following reactions. 5
(i) Cannizaro's reaction.
(ii) Cross aldol condensation.
(c) How will you convert?
(i)
Methyl cyanide to acetamide
(ii) Acetaldehyde to but 2 enal.
(iii) Ethyl benzene to benzoic acid.
OR
[B]
(a) A compound a on oxidation
given B (C2H4O2). A reacts with Dil NaOH
and on Subsequent heating forms C. C on
catalytic hydrogenation gives D.
Identify A, B, C and D and write down the reaction
involved.
(b) Write short notes on.
(i) Clemmenson reaction.
(ii)
Hell – Volhard – Zelinsky reaction.
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DR
SUDHIR TOMAR
somebody shoule comment pls
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