Class 12 Chemistry Model Question Paper 2078
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School Leaving Certificate
Examination 2078
Grade: XII
Subject: Chemistry ; Subject
Code: 302
Full marks: 75 (11 marks Obj+ 64
marks Sub)
Time: 3 Hours
Group A:
Multiple Choice Questions (11*1=11)
Time 25 Minutes
Tick the correct answer.
1.What is the equivalent weight
of H3 PO3 the
reaction;
2NaOH + H3 PO3 -- Na 2HPO3 + 2H2O
A) 2M
B) M/I
C) M/2
D)M/3
2. The solubility product of
chalk is 9.3 * 10-8 What is its solubility in gram per liter?
4)3.04*10-1
3)3.04*10-2
C) 3.04 * 10-3
D) 3.04 * 10-4
3. What is the concentration of
N2O5 in the following first order reaction in which the rate
is 2.4 * 10-5 mol/L and rate constant is 3.0*10-5 S-1
?
N2O5 ----- 4NO2
+ O2
A) 0.04
B) 0.8
C) 1.2
D) 1.4
4. What happens when the lead
storage battery is discharged?
A) SO2 is evolved
B) PbSO4 is consumed
C) Lead is formed
D) H2SO4 is
consumed
5. What is the general
electronic configuration of transition metal?
A) (n-1) s2p6d1
to 10 ns0 to 2
B) (n-1) s2p6ns2
np1
C) (n-1) s2p6d5
ns1
D) (n-1) s2p6
ns1
6. Which of the following ore is
concentrated by forth-flotation process?
A) Hematite
B) Siderite
C) Galena
D) Malachite
7. Which of the following
products is obtained when nitrobenzene is electrolytically reduced?
A) P-aminophenol
B) azobenzene
C) azoxybenzene
D) hydrazobenzene
8) Which of the following
compounds is pi-bonded organo-metallic compound which has ethene as one of its
component and is the first synthesized organometallic compound?
A) Zeise's salt
B) Ferrocene
C) Dibenzene chromium
D) Tetraethyl tin
9) What effects does calcium sulphate have on cement ?
A) Retards setting action
B) Acts as flux
C) Imparts color
D) Reduces strength
10. Removal of which of the
following leads to higher fiber-fiber bonding strength in paper?
A) Softwood
B) Hardwood
C) Lignin
D) Pulp
11. In the figure given below which one is correct?
A) Alpha ray deviates towards A.
beta rays deviate towards C and gamma rays direct towards B
B) Alpha rays direct towards B.
beta rays deviate towards C and gamma rays towards A
C) Alpha rays deviate towards
C, beta rays direct towards B and gamma rays towards A
D) Alpha rays deviate towards C,
beta rays deviate towards A and gamma rays direct towards B.
School Leaving Certificate
Examination 2078
Grade: XII
Subject: Chemistry
Subject Code: 302 Time: 3 Hours
Full :75(11 marks Obj+64 marks
Sub)
Attempt all the questions.
Group B:
Short Answer Questions (8*5=40 )
1. Standard solution of Na2CO3
is used to determine the strength of during Titration.
A) How is the completion of the
reaction in this titration detected? Is the solution prepared from Na2CO3
primary standard? Why? [1+1]
B)2.16 g of pure Na2CO3
is added to 400 ml deci-normal solution of H2SO4 . How
many grams of H2SO4 is further required to neutralize the
resultant solution completely? [3]
A) Derive the relation k = log
2.303/t *log a/(a - x). Show that for the first order reaction the time
required for half the change (half life period) is independent of the initial
concentration. (2+1)
B) A first order reaction is
50% completed in 1.26*10145 How
much time would it take for 90 % completion? (2)
2.Study the following data for
the thermodynamic process
H 2 O(l) -------------H 2 O(s) at different temperatures and at 1 atmospheric pressure.
a) Calculate the total entropy
of the universe at given condition 3. (1)
b. Can we predict the
spontaneity of the given reaction at 00 C?(1)
c. Calculate the equilibrium
constant for the fusion of ice at 10 C . What is the effect of
temperature for the entropy change of reaction? (2+1)
3. The figure shows the octahedral distortion of d-block orbital in the presence of ligand.
a) Why does octahedral disorder
occur in the presense of ligand ? Explain on the basis of CFT ? (2)
b) On the basis of given distortion
, how can you explain [ Cu(H20)6]++ is blue colored
complex . (1)
c) Out of Fe++ and Fe+++
which one is more stable ? Explain on the basis of distortion seen in the above
figure. (1)
d) why do such elements which
give such splitting show good catalytic properties ? (1)
4. X is an ore of a metal M. X on
calcination gives black precipitate (W) of metal oxide which belongs to group
II of basic radical in qualitative analysis. X on roasting gives the metal (M) and
a gas as major byproduct. The gas when passed through an acidified K2Cr2O7
solution turns green.
a. Identify the metal X. (1)
b. Write the reaction involved
during calcination of X. (1)
c. Write the action of the gas on
acidified K2Cr2O7 (1)
d. Convert metal X into it's
vitriol. (2)
5. The given table shows the compounds and their molecular formula. How can you convert P to Q, where Q is a compound in which two methyl groups are substituted at adjacent carbons? How is P obtained from T, where T is secondary alcohol? Write the reactions involved in the conversion of P into R and S? [5x1=5]
OR
An aromatic compound [A] in which
one chlorine atom is substituted at benzene ring. When the compound [A] is
heated with 2, 2, 2-trichloro ethanal in presence of conc. H2SO4
gives an insecticide [B] The compound [A] when treated with an acid chloride
containing two carbon atoms in the presence of anhydrous AlCl3 ,
gives [C].
a. Identify B and C. (1+1)
b. Reaction of aq. NaOH on the
compound [A] is more difficult than with chloroethane, justify with a suitable
explanation. (2)
c. How would you obtain compound
A from benzene diazonium chloride? (1)
6. A list of compounds are given
as follows:
p-hydroxyazobenzene, C6H5N2Cl
, C6H5NH2 , C6H5NO2
, C6H6
From the above list of compounds,
prepare a sequence of reaction chain with suitable conditions and reactions. (1
+ 1 + 1 + 1)
7. Write down the isomeric
alcohols of C3H8O and their IUPAC name. How would you
apply Victor Meyer's test to distinguish these isomers? (2+3)
8. A) Define condensation
polymerization. Write the molecular structures monomers of Bakelite. (1+2)
B) Differentiate between OPC and
PPC cement. (2)
Group C:
Long Answer Questions (
3*8=24)
9. (A) What amount of Zn(OH)2
will be precipitated out at 250 C if 100 ml of 0.22gm NaOH is added
to 1 liter of a saturated solution of Zn(OH)2 ?Precipitate is
obtained in this reaction. why?
[Solubility product of Zn(OH)2
at 2500 C is 1.8*10-14 .]
(B) Potassium hydroxide having pH
8 is diluted 1000 times. Calculate the pH of the diluted base. (3)
Or
A)Calculate the heat of formation of ethyl alcohol from given data. (4)
B) The standard electrode
potential for the following electrode reaction at standard state is
a. Write the cell notation
indicating anode and cathode. (1)
b. With IM solution of ion at 250
C and 1 atm. pressure, what will be the cell potential? (1)
c. Calculate the free energy
change in the reaction. (1)
d. Can we store AgNO3
solution in a copper vessel? (1)
10, (A) A primary alcohol with
molecular wt. 46 is boiled with sodium hydroxide and iodine. When the same
alcohol is heated with ethanoic acid in presence of conc.H2SO4
, one of the derivatives of carboxylic acid is obtained. Write the reactions
involved in both conditions.What would be the product obtained when the same
alcohol is heated with Conc H2SO4 ?How would you
distinguish the above alcohol from methanol? [1 + 1 + 1 + 1 + 1 = 5]
(B) An aromatic compound known as
oil of mirabane is prepared from benzene. a. a.What product would you obtain
when the compound is electrolyzed in acidic medium? (1)
b. Give the complete reaction for
the conversion of the compound into yellow dye. (2)
11.(A) An organic compound is
used in the given figure to preserve museum specimens and also to prepare
urinary antiseptics.
a. Write the reaction when the
compound is heated with concentrated sodium hydroxide. (1)
b. Draw the structure of
urinary antiseptic (1)
c.Write the chemical reaction
that would occur when the given preservative is treated with phenol in acidic
medium. (2)
d. How would you obtain the
preservative from methanol? (1)
(B) A carbonyl compound with
molecular formula C3H6O (it does not give silver mirror
test) has treated with a compound Y which gives Z. Z. on bydrolysis in acidic
medium gives 2 hydroxy-2-methyl propanoic acid. Identify the carbonyl compound,
Y and Z with proper reactions. [1+1+1]
or
(A) Starting from compound P.
how do the reactions proceed ahead to obtain T which gives benzene where R is
aniline? Complete the reaction sequence with suitable conditions. [5x1=5]
(B) Arrange the given compounds
according to their ascending order of acidic strength and justify your order.
CH3CH₂COOH.
C6H5COOH
CICH₂CH₂COOH
[1+1+1]
The End
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