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SAMPLE PAPER -3 CLASS: XII SUBJECT: CHEMISTRYTHEORY
(043) TIME: 3 Hrs MM: 70 |
General Instructions:
Read the following instructions
carefully.
(a) There are 33 questions in this
question paper with internal choice.
(b) SECTION A consists of 16
multiple -choice questions carrying 1 mark each.
(c) SECTION B consists of 5 short
answer questions carrying 2 marks each.
(d) SECTION C consists of 7 short
answer questions carrying 3 marks each.
(e) SECTION D consists of 2
case-based questions carrying 4 marks each.
(f) SECTION E consists of 3 long
answer questions carrying 5 marks each.
(g) All questions are compulsory.
(h) Use of log tables and calculators is not allowed.
SECTION A
The following questions are multiple-choice questions with one correct answer.
Each question carries 1
mark. There is no internal choice in this section.
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1. |
The amount of electricity required to deposit 1 mol of aluminum from
a solution of AlCl3 will be |
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2. |
Tertiary amines have
lowest boiling points amongst isomeric amines because: (a) they have highest
molecular mass. (b) they do not form
hydrogen bonds. (c) they are more polar in
nature (d) they are most basic in
nature |
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3. |
What
is the building block of a nucleic acid? a) Amino acid c)
Monosaccharide d) Nucleotide |
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4. |
Which of the following
will not give aldol condensation? (a) Phenyl acetaldehyde(b)
2-Methylpentanal (c) Benzaldehyde (d)
1-Phenylpropanone |
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5. |
Mischmetal contains: (a) a lanthanoid element
and Zinc (b) an actinoid element and Zinc (c) a lanthanoid element
and iron (d) an actinoid element
and Mg |
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6. |
CH3CH2OH
can be converted into CH3CHO by: (a) catalytic hydrogenation (b)treatment
with LiAlH4 (c) treatment with pyridinium
chlorochromate (d) treatment
with KMnO4 |
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7. |
The
rate constant of a reaction is 1.2 x 10-2s-1, the order
of reaction is: (a)
0 (b) 1(c) 0.5 (d) 2 |
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8. |
Cu+ is less stable than Cu2+ in
aqueous solution. This is because of (a) More negative
Hydration enthalpy of Cu+ ion (b) More negative
Hydration enthalpy of Cu2+ ion (c) Less negative
Hydration enthalpy of Cu2+ ion (d) Less enthalpy
atomization of Cu |
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9. |
A first order reaction has
a rate constant1.15×10-3 s-1. How long time will 5g of
this reactant take to reduce to 3g? (a)444 (b) 400s (c) 528s
(d) 669s |
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10. |
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11. |
Which one of the following
compounds is more reactive towards SN1 reaction? (a) CH2=CHCH2Br
(b) C6H5CH2Br
(c) C6H5CH (C6H5)Br
(d) C6H5CH(CH3) Br |
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12. |
Methyl ketones are usually
characterized through (a) Tollens's reagent (b)
Iodoform test (c) Schiff’s test (d) Benedict test. |
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In
questions (13 to 16), Given below are two statements labeled as Assertion
(A) and Reason (R). Select
the most appropriate answer in questions 13 to 16, from the options given
below: (a) Both A and R are true and R is the correct
explanation of A (b)
Both A and R are true but R is not the correct explanation of A. (c)
A is true but R is false.(d) A
is false but R is true. |
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13. |
Assertion (A): D (+)
Glucose is dextrorotatory in nature. Reason (R): ‘D’ represents
its dextrorotatory nature. |
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14. |
Assertion
(A): During electrolysis of aqueous copper sulphate solution using copper
electrodes hydrogen gas is released at the cathode. Reason(R):
The electrode potential of Cu2+/Cu is greater than H+/ H2 |
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15. |
Assertion (A): Phenol is
more reactive than benzene towards electrophilic substitution reaction. Reason (R): In the case of
phenol, the intermediate carbocation is more resonance stabilized. |
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16. |
Assertion (A): (CH3)3C-COOH
does not undergo HVZ reaction. Reason (R): It does not
contain any α- hydrogen |
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SECTION B
This section contains 5 questions with internal choice in one question.
The following questions are very short answer
type and carry 2 marks each.
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17. |
Define Osmotic Pressure.
Why is osmotic pressure used for the determination of molar masses of
macromolecules like protein? |
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18. |
A reaction is second order
in A and first order in B. (i) Write the differential
rate equation. (ii) How is the rate
affected on increasing the concentration of A three times? |
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19. |
Account for the following: (i) The C – Cl bond length
in chlorobenzene is shorter than that in CH3– Cl (ii) Grignard reagent
should be prepared under anhydrous conditions. |
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20. |
Arrange the following
compounds in increasing order of their property as indicated: (a)
CH3COCH3, C6H5COCH3, CH3CHO
(reactivity towards nucleophilic addition reaction)
(b)
Cl—CH2—COOH,
F—CH2—COOH,
CH3—COOH
(acidic character) OR Convert
the following: (a)
Benzene to m-nitrobenzaldehyde (b)
Bromobenzene to benzoic acid |
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21. |
Differentiate between the
following: (i) Amylose and
amylopectin (ii) Peptide linkage and
glycosidic linkage |
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SECTION C
This section contains 7 questions with internal choice in one question.
The following
questions are short answer types and carry 3 marks each.
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22. |
For the standard
cell Cu(s)/Cu2+(aq) || Ag+(aq)/Ag(s)
(i) Identify the cathode
and the anode as the current is drawn from the cell. (ii) Write the reaction
taking place at the electrodes. (iii) Calculate the
standard cell potential. E°(Cu2+/Cu) = +0.34V, E° (Ag+/Ag)=
+0.80 V |
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23. |
Give the formula of each
of the following coordination entities: (a)Co3+ion is
bound to one Cl-, one NH3molecule and two bidentate ethylene
diamine (en) molecules. (b) Ni2+ion is
bound to two water molecules and two oxalate ions. Write the name and
magnetic behaviour of each of the above coordination entities. |
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24. |
Write
the name of the reaction, structure and IUPAC name of the product formed when
(any 2): (a) phenol reacts with CHCl3in
the presence of NaOH followed by hydrolysis. (b) CH3CH2CH(CH3)CH(CH3)ONa
reacts with C2H5Br. (c) CH3CH2CN
reacts with stannous chloride in the presence of hydrochloric acid followed
by hydrolysis. |
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25. |
The decomposition of phosphine, 4PH3(g) ®P4(g) +
6H2(g)
has the rate law, Rate = k[PH3]. The rate constant is 6.0 × 10-4
s-1 at 300 K and activation energy is 3.05 × 105J mol-1.
Calculate the value of rate constant at 310 K. [Given: R = 8.314 J K-1mol-1] |
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26. |
(a)Haloalkanes undergo
nucleophilic substitution whereas haloarenes do not undergo it easily.
Explain. (b) The product formed
during SN1 reaction is a racemic mixture. Explain. |
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27. |
An organic compound ‘A’
which has characteristic odor, on treatment with NaOH forms two compounds
‘B’ and ‘C’. Compound ‘B’ has the molecular formula C7H8O
which on oxidation CrO3gives back compound ‘A’. Compound ‘C’ is
the sodium salt of the acid. ‘C’ when heated with soda lime yields an
aromatic hydrocarbon ‘D’. Deduce the structures of ‘A’, ‘B’, ‘C’ and ‘D’. |
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28. |
(a)Complete the following
statement: In sucrose, the two
monosaccharide units are held together by _____(A) linkage between C1of _______(B) and C2 of _______ (C). Identify
A, B & C. (b) Sucrose is dextrorotatory,
but after hydrolysis the mixture is levorotatory. |
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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.
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29. |
Complex compounds play an
important role in our daily life. Werner’s theory of complex compounds says
every metal atom or ion has primary valency (oxidation state) which is
satisfied by negatively charged ions, ionizable where secondary valency
(coordination number) is non-ionizable, satisfied by ligands (+ve, –ve,
neutral) but having lone pair. Primary valency is non-directional, and secondary
valency is directional. Complex compounds are named according to the IUPAC system.
Valence bond theory helps in determining shapes of complexes Based on
hybridization, magnetic properties, outer or inner orbital complex. Complex
show ionization, linkage, solvate and coordination isomerism also called
structural isomerism. Some of them also show stereoisomerism i.e. geometrical
and optical isomerism. Ambidentate ligand are essential to show linkage
isomerism. Polydentate ligands form more stable complexes then unidentate
ligands. There are called chelating agents. EDTA is used to treat lead
poisoning, cis-platin as anticancer agents. Vitamin B12 is complex of cobalt.
Haemoglobin, oxygen carrier is complex of Fe2+and chlorophyll
essential for photosynthesis is complex of Mg2+. (a) What is the oxidation state of Ni in [Ni(CO)4]?
OR Write the coordination number in the
given complex: [Cr(H2O)2(C2O4)2]- (b) Indicate the type of isomerism exhibited by
the following complex: [Co(NH3)5(NO2)](NO3)2 (c)
Out of cis – [Pt(en)2Cl2]2+and
trans (Pt(en)2Cl2)2+which one shows optical
isomerism and why? |
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30. |
Conductors allow the
passage of electric current through them. Metallic and electrolytic are the
two types of conductors. Current carriers in metallic and electrolytic
conductors are free electrons and free ions respectively. Specific
conductance or conductivity of the electrolyte solution is given by the
relation: Ƙ= c x l/A where c = 1/R is the conductance and l/A is the cell
constant. The molar conductance of strong electrolytes depends on concentration: Λm= Λ°m− b√c,Λm= molar
conductance at infinite dilution, c= concentration of the solution, b =
constant. The degree of dissociation of weak electrolytes is calculated as:α
= 𝜆𝑚/𝜆𝑚∞ (a) Out of specific
conductance and molar conductance, which one of the following decreases on dilution
of electrolyte solution and why? (b) The resistance of a conductivity cell containing 0.001M KCl solution
at 298 K is 1500 M. What is the cell constant if the conductivity of 0.001M KCl
solution at 298 K is 0.146 × 10−3S cm−1? (c) Calculate ⋀°m NH4OH from the following values.⋀°m for Ba(OH)2,BaCl2, NH4Cl
are 257.6, 240.6, 129.8 S cm2mol-1respectively. OR (i)Write the correct order
of molar conductance at infinite dilution for LiCl, NaCl and KCl. (ii)State Kohlrausch’s
law. |
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SECTION E
The following questions are long answer type and carry 5 marks each.
All questions have an internal choice.
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31. |
(a) What is the effect of
pressure on the solubility of glucose in water? (b) Smith collected a 20
mL each of fresh water and sea water. He observed that one sample labeled “A”
froze at 0 oC
while the other “B” at -1.5oC. He forgot which of the two, “A” or “B” was
sea water. Help him identify which container contains sea water, giving
rationalization for your answer. (c) Calculate Van't Hoff
factor for an aqueous solution of K3 [Fe(CN)6] if the degree of dissociation (α)
is 0.852. What will be boiling point of this solution if its concentration is
1 molal? (Kb=0.52 K kg/mol) OR (a)
What type of deviation from Raoult’s Law is expected when phenol and
aniline are mixed with each other? What change in the net volume of the
mixture is expected? Graphically represent the deviation. (b)
The vapour pressure of pure water at a certain temperature is 23.80 mm
Hg. If 1 mole of a non- volatile non- electrolytic solute is dissolved in
100g water, Calculate the resultant vapour pressure of the solution. |
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32. |
(a) Account for the
following: (i) pKbof
aniline is more than that of methylamine. (ii)Although amino group
is o, p−directing in aromatic electrophilic substitution reactions, aniline
on nitration gives a substantial amount of m- nitroaniline. (b) Arrange the following
in: (i) In decreasing order of
basic strength in gas phase: C2H5NH2, (C2H5)2NH, (C2H5)3N and NH3 (ii) increasing order of
solubility in water C2H5Cl,
C2H5NH2, C2H5OH (iii) decreasing boiling
point CH3COOH, C2H5OH,
CH3NH2, CH3OCH3 OR (a) Describe a method for
the identification of primary, secondary and tertiary amines. Also write
chemical equations of the reactions involved. (b)
Write short notes on the
following: (i)
Carbylamine reaction (ii) Hofmann’s bromamide reaction |
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33. |
Attempt any five of the following: (a) Transition metals and
many of their compounds show paramagnetic behaviour.Why? (b) The enthalpies of
atomization of transition metals are high.Why? (c) Transition metals form
alloys and interstitial compounds. Why? (d)
The second ionization enthalpies of chromium and manganese are 1592 and
1509 kJ/mol respectively. Explain the lower value of Mn. (e)
Give two similarities in the properties of Sc and Zn. (f)
What is actinoid contraction? What causes actinoid contraction? (g)
What is the oxidation state of manganese in manganate and permanganate ion? |
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