Q.P. Code: 43/23/1
Roll No.
Q.P. Code: 43/23/1
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CLASS XII
CHEMISTRY (043)
(Theory)
Time allowed: 3 hours
Maximum Marks: 70
General Instructions:
(i)
(ii)
(iii)
(iv)
(v)
(vi)
(vii)
(viii)
There are 35 questions in this question paper with internal choice.
SECTION A consists of 18 multiple-choice questions carrying 1 mark each.
SECTION B consists of 7 very short answer questions carrying 2 marks each.
SECTION C consists of 5 short answer questions carrying 3 marks each.
SECTION D consists of 2 case- based questions carrying 4 marks each.
SECTION E consists of 3 long answer questions carrying 5 marks each.
All questions are compulsory.
Use of log tables and calculators is not allowed
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SECTION A
1. Zinc is coated over iron to prevent the rusting of iron because
a) EO Zn2+/Zn =EO Fe 2+/Fe
b) EO Zn2+/Zn < EO Fe2+/Fe
c) EO Zn2+/Zn > EO Fe 2+/Fe
d) None of the above
2. In electrochemical process a salt bridge is used
a) As a reducing agent
b)As an oxidising agent
c) To complete the circuit so that electrons can flow
d) None of these
3. What is the concentration of the reactant in a first order reaction when the rate of the
reaction is 0.6 s-1 and the rate constant is 0.035?
a) 26.667 M
b) 17.143 M
c) 26.183
d) 17.667 M
4. The activation energy of a chemical reaction can be determined by
a) Evaluating velocities of reaction at two different temperatures
b) Changing concentration of reactants
c) using catalyst
d) Evaluating rate constants at two different temperatures
5. Zr and Hf have almost equal atomic and ionic radii because of:
a) Diagonal relationship
b) Lanthanoid contraction
c) Actinoid contraction
d) Belonging to the same group
6 . Which of the following is strong oxidising agent?
a) Mn3+
b) Ti3+
c) Zr3+
d) Cr3+
7. The magnetic moment of 2.83 BM is given by which of the following
ion?
a) Ti3+ b) Ni2+
c) Cr3+
d) Mn2+
8. Interstitial compounds are formed when small atoms are trapped inside the crystal lattice
of metals. Which of the following is not the characteristic property of interstitial
compounds?
a) The have high melting point in comparison with pure compounds
b) They are very hard
c)They retain metallic character
d) They are chemically inert
9. Chelating ligands have two or more than two donor atoms to bind to a single metal ion.
Which of the following is not a chelate ligand?
a) thiosulphato
b) oxalato
c) edta
d) ethane 1,2 diamine
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10. Which one has the highest molar conductivity?
a) [Pt (NH3)2 Cl2] b) [Co (NH3)4 Cl2] Cl
c) K4[Fe (CN)6]
d) [Cr (H2O)6] Cl3
11. The order of reactivity of the following alcohols with halogen acids is
I,
ii
iii.
(i)>(ii)>(iii)
b) (iii) > (ii) > (i)
c) (ii) > (i) > (iii)
d) (i) >(iii) >(ii)
12. Osmotic pressure of a solution is 0.0821 atm at a temperature of 300 K. The
concentration in moles/litre will be
a) 0.33
b) 0.666
c) 0.3 × 10 -2
d) 3
13. Which of the following polymer is stored in the liver of animals?
a) amylose
b) cellulose
c) amylopectin
d) glycogen
14. The correct increasing order of basic strength for the following compounds is
i.
a) (ii)<(iii)<(i)
ii
b) (iii)<(i)<(ii)
iii.
c) (iii)<(ii)<(i)
d) (ii)<(i)<(iii)
In the following questions a statement of assertion followed by a statement of reason is
given. Choose the correct answer out of the following choices
(i)Assertion and Reason both are correct statements but reason does not explain
assertion
(ii) Assertion and Reason both are correct statements and reason explains the
assertion
(iii)Both Assertion and Reason are wrong statements
(iv) Assertion is correct statement and reason is wrong statement.
(v) Assertion is wrong statement and reason is correct statement.
15. Assertion: Hoffmann’s Bromamide reaction is given by primary amides
Reason:
primary amines are more basic than secondary amines.
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16. Assertion: Vitamin D can be stored in our body
Reason:
Vitamin D is fat soluble vitamin
17. Assertion: In presence of enzyme, substrate molecule can be attacked by reagent
molecule effectively
Reason:
Active sites of enzymes hold the substrate molecule in a suitable position
18. Assertion: The alpha- hydrogen atom in carbonyl compound is less acidic
Reason:
The anion formed after the loss of alpha- hydrogen is resonance
stabilised.
SECTION B
19. Explain the term: a) Rate constant b) Half-life period of reaction
20. Write the IUPAC nomenclature for the following compounds:
a)
b) Complete the following reaction
21. Define with equation
a)Riemer-Tiemann Reaction
b) Williamson’s Synthesis
22. Name the following coordination compounds according to IUPAC system of
nomenclature :
a) [Co(NH3)4 (H2O)Cl]Cl2
b) [CrCl2(en)2]Cl
23. Write the structures of the main products when
Ethanol reacts with the following reagents:
a) HCN
b) H2N-NH2 /H+
c) LiAlH4
24. Give reasons for the following
a) (CH3)2NH is more basic than (CH3)3N in an aqueous solution
b) Primary amines have higher boiling point than tertiary amines
25. Give one chemical test to distinguish between the following pairs of compounds:
a) Methylamine and dimethylamine.
b) Secondary and tertiary amines.
SECTION C
This section contains 5 questions with internal choice in two questions. The
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following questions are short answer type and carry 3 marks each.
26. A 0.01 m aqueous solution of AlCl3 freezes at -0.068O C. Calculate the percentage of
dissociation. {Kf of water=1.86K Kg/mol]
27. Give reason
i)Transition elements and their compounds show catalytic activities.
ii)Study of Actinoid is not so smooth.
iii)Zn,Cd, and Hg are soft and have low melting point .
( OR)
iv)Ce4+ is a strong oxidising agent
28. Write the hybridization, isomerism and magnetic behaviour of the complex
[Ni(CO)4].
29. Give reasons for the following:
a) The presence of –NO2 group at ortho and para position increases the reactivity of
haloarenes towards nucleophilic substitution reactions.
b) p-dichlorobenzene has higher melting point than that of ortho or meta isomer.
c) Thionylchloride method is preferred for preparing alkyl chloride from alcohols
30. a) Calculate the mass of the compound (molar mass of benzene=256g/mol) to be
dissolved in 75g of benzene to lower its freezing point by 0.48K (Kf=5.12Kkg/mol)
b) Define Abnormal molar mass.
SECTION D
The following questions are case-based questions. Each question has an internal
choice and carries 4 (1+1+2) marks each. Read the passage carefully and answer the
questions that follow.
31. Read the passage given below and answer the following questions :
Carbohydrates are primarily produced by plants and form a very large group of
naturally occurring organic compounds. Some common examples of carbohydrates
are cane sugar, glucose, starch, etc. Most of them have a general formula,
Cx(H2O) y, and were considered as hydrates of carbon from where the name
carbohydrate was derived. For example, the molecular formula of glucose
(C6H12O6) fits into this general formula, C6(H2O)6. But all the compounds which fit
into this formula may not be classified as carbohydrates. For example, acetic acid
(CH3COOH) fits into this general formula, C2(H2O)2 but is not a carbohydrate.
Similarly, rhamnose, C6H12O5 is a carbohydrate but does not fit in this definition. A
large number of their reactions have shown that they contain specific functional
groups. Chemically, the carbohydrates may be defined as optically active
polyhydroxy aldehydes or ketones or the compounds which produce such units on
hydrolysis
a) What are monosaccharides?
b) What is glycogen? How it is different from starch?
c) Write the product obtained when D-Glucose reacts with NH2OH
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OR
Write the product obtained when D-Glucose reacts with HCN
32. Read the passage given below and answer the following questions:
Alcohols and phenols are formed when a hydrogen atom in a hydrocarbon, aliphatic
and aromatic respectively, is replaced by –OH group. These classes of compounds
find wide applications in industry as well as in day-to-day life. For instance, have you
ever noticed that ordinary spirit used for polishing wooden furniture is chiefly a
compound containing hydroxyl group, ethanol. The sugar we eat, the cotton used for
fabrics, the paper we use for writing, are all made up of compounds containing –OH
groups. Just think of life without paper; no note-books, books, newspapers, currency
notes, cheques, certificates, etc. The magazines carrying beautiful photographs and
interesting stories would disappear from our life. It would have been really a
different world. In alcohols, the oxygen of the –OH group is attached to carbon by a
sigma (σ) bond formed by the overlap of a sp3 hybridised orbital of carbon with a sp3
hybridised orbital of oxygen.
a. How will you synthesise the following alcohol from an appropriate
alkene?
b. What happens when salicylic acid is treated with acetic anhydride?
c. How do you convert the following
Phenol to anisole
(OR)
Ethanol to propan-2-ol
SECTION E
33. a) When a steady current of 2A was passed through two electrolytic
cells A and B containing electrolytes ZnSO4 and CuSO4 connected in
series, 2g of Cu were deposited at the cathode of cell B. How long did the current
flow? What mass of Zn was deposited at cathode of cell A?
[Atomic mass:Cu=63.5gmol−1,Zn=65gmol−1;1F=96500Cmol−1]
b) Write the anode and the cathode reaction occurring in lead storage
battery?
(OR)
a)The conductivity of 0.001 M acetic acid is 4 × 10-5 S/cm. Calculate the dissociation
constant of acetic acid, if molar conductivity at infinite dilution for acetic acid is
390 Scm2/mol.
b)State Kohlrausch law of independent migration of ions. Why does the conductivity
of a solution decrease with dilution?
34. a) For the reaction ; 2A + B → A2B, the reaction rate = k [A][B]2 with k = 2·0 x
10- 6 mol-2 L2 s-1. Calculate the initial rate of the reaction when [A] = 0·1 mol
L-1; [B] = 0·2 mol L-1. Also calculate the reaction rate when [A] is reduced to
0·06 mol L-1.
Sol:
b) Derive the First order rate equation.
(OR)
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a) The initial concentration of the first-order reaction,
N2O5(g)→2NO2(g)+1/2O2(g) was 1.24 x10-2 mol L -1 at 300K.The concentration of
N2O5 after one hour was 0.20x10-2molL-1. Calculate the rate constant of the
reaction at 300K. [log6.2=0.7923]
b) i) For a reaction R→P, half-life t1/2is observed to be independent of the initial
concentration of reactants. What is the order of reaction?
ii) Identify the order of a reaction if the units of its rate constant are L-1mols-1
35. a) Identify A and B in the following sequence of reaction:
An alkene ‘A’ with molecular formula C5H10 on ozonolysis gives a mixture of two
compounds ‘B’ and ‘C’. Compound ‘B’ gives positive Fehling test and also react with
iodine and NaOH solution. Compound ‘C’ does not give Fehling solution test but
forms iodoform. Identify the compounds ‘A’, ‘B’ and ‘C’.
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