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Page 1
CBSE XII | CHEMISTRY
Board Paper – 2017
CBSE
Class XII Chemistry
Board Paper – 2017
Time: 3 Hours Total Marks: 70
General Instructions:
(i) All questions are compulsory.
(ii) Question numbers 1 to 5 are very short answer questions and carry 1 mark
each.
(iii) Question numbers 6 to 10 are short answer questions and carry 2 marks
each.
(iv) Question numbers 11 to 22 are also short answer questions and carry 3
marks each.
(v) Question number 23 is a value based question and carries 4 marks.
(vi) Question numbers 24 to 26 are long answer questions and carry 5 marks
each.
(vii) Use log tables, if necessary. Use of calculators is not allowed.
1. Write the formula of an oxo-anion of Manganese (Mn) in which it shows the
oxidation state equal to its group number. [1]
2. Write IUPAC name of the following compound-:
(CH3CH2)2NCH3 [1]
3. For a reaction R ? P, half-life (t1/2) is observed to be independent of the initial
concentration of reactants. What is the order of reaction? [1]
4. Write the structure of 1-Bromo-4-chlorobut-2-ene. [1]
5. Write one similarity between Physisorption and Chemisorption. [1]
6. Complete the following reactions: [1+1=2]
(i) NH3 + 3Cl2 (excess) ?
(ii) XeF6 + 2H2O ?
OR
What happens when
(i) (NH4)2Cr2O7 is heated?
(ii) H3PO3 is heated?
Write the equations.
7. Define the following terms: [1+1=2]
(i) Colligative properties
(ii) Molality (m)
Page 2
CBSE XII | CHEMISTRY
Board Paper – 2017
CBSE
Class XII Chemistry
Board Paper – 2017
Time: 3 Hours Total Marks: 70
General Instructions:
(i) All questions are compulsory.
(ii) Question numbers 1 to 5 are very short answer questions and carry 1 mark
each.
(iii) Question numbers 6 to 10 are short answer questions and carry 2 marks
each.
(iv) Question numbers 11 to 22 are also short answer questions and carry 3
marks each.
(v) Question number 23 is a value based question and carries 4 marks.
(vi) Question numbers 24 to 26 are long answer questions and carry 5 marks
each.
(vii) Use log tables, if necessary. Use of calculators is not allowed.
1. Write the formula of an oxo-anion of Manganese (Mn) in which it shows the
oxidation state equal to its group number. [1]
2. Write IUPAC name of the following compound-:
(CH3CH2)2NCH3 [1]
3. For a reaction R ? P, half-life (t1/2) is observed to be independent of the initial
concentration of reactants. What is the order of reaction? [1]
4. Write the structure of 1-Bromo-4-chlorobut-2-ene. [1]
5. Write one similarity between Physisorption and Chemisorption. [1]
6. Complete the following reactions: [1+1=2]
(i) NH3 + 3Cl2 (excess) ?
(ii) XeF6 + 2H2O ?
OR
What happens when
(i) (NH4)2Cr2O7 is heated?
(ii) H3PO3 is heated?
Write the equations.
7. Define the following terms: [1+1=2]
(i) Colligative properties
(ii) Molality (m)
CBSE XII | CHEMISTRY
Board Paper – 2017
8. Draw the structures of the following: [1+1=2]
(i) H2S2O7
(ii) XeF6
9. Calculate the degree of dissociation ( a) of acetic acid if its molar conductivity
( ?m) is 39.05 S cm
2
mol
?1
. [2]
Given ?
o
(H
+
) = 349.6 S cm
2
mol
?1
and ?
o
(CH3COO
?
) = 40.9 S cm
2
mol
?1
10. Write the equations involved in the following reactions: [2]
(i) Wolff-Kishner reduction
(ii) Etard reaction
11. A 10% solution (by mass) of sucrose in water has freezing point of 269.15 K
Calculate the freezing point of 10% glucose in water, if freezing point of pure
water is 273.15 K. [3]
Given: (Molar mass of sucrose = 342 g mol
?1
)
(Molar mass of glucose = 180 g mol
?1
)
12.
(a) Calculate the mass of Ag deposited at cathode when a current of 2 amperes was
passed through a solution of AgNO3 for 15 minutes. [2+1=3]
(Given: Molar mass of Ag = 108 g mol
?1
1F = 96500 C mol
?1
)
(b) Define fuel cell.
13.
i. What type of isomerism is shown by the complex [Co(NH3)6] [Cr(CN)6]?[1 ?3=3]
ii. Why a solution of [Ni(H2O)6]
2+
is green while a solution of [Ni(CN)4]
2 ?
is
colourless? (At. no. of Ni = 28)
iii. Write the IUPAC name of the following complex: [Co(NH3)5(CO3)]Cl
14. Write one difference in each of the following: [1 ?3=3]
(i) Lyophobic sol and Lyophilic sol
(ii) Solution and Colloid
(iii) Homogeneous catalysis and Heterogeneous catalysis
15. Following data are obtained for the reaction: [3]
N2O5 ? 2NO2 + ½ O2
t/s 0 300 600
[N2O5]/mol L
?1
1.6 ? 10
?2
0.8 ? 10
?2
0.4 ? 10
?2
Page 3
CBSE XII | CHEMISTRY
Board Paper – 2017
CBSE
Class XII Chemistry
Board Paper – 2017
Time: 3 Hours Total Marks: 70
General Instructions:
(i) All questions are compulsory.
(ii) Question numbers 1 to 5 are very short answer questions and carry 1 mark
each.
(iii) Question numbers 6 to 10 are short answer questions and carry 2 marks
each.
(iv) Question numbers 11 to 22 are also short answer questions and carry 3
marks each.
(v) Question number 23 is a value based question and carries 4 marks.
(vi) Question numbers 24 to 26 are long answer questions and carry 5 marks
each.
(vii) Use log tables, if necessary. Use of calculators is not allowed.
1. Write the formula of an oxo-anion of Manganese (Mn) in which it shows the
oxidation state equal to its group number. [1]
2. Write IUPAC name of the following compound-:
(CH3CH2)2NCH3 [1]
3. For a reaction R ? P, half-life (t1/2) is observed to be independent of the initial
concentration of reactants. What is the order of reaction? [1]
4. Write the structure of 1-Bromo-4-chlorobut-2-ene. [1]
5. Write one similarity between Physisorption and Chemisorption. [1]
6. Complete the following reactions: [1+1=2]
(i) NH3 + 3Cl2 (excess) ?
(ii) XeF6 + 2H2O ?
OR
What happens when
(i) (NH4)2Cr2O7 is heated?
(ii) H3PO3 is heated?
Write the equations.
7. Define the following terms: [1+1=2]
(i) Colligative properties
(ii) Molality (m)
CBSE XII | CHEMISTRY
Board Paper – 2017
8. Draw the structures of the following: [1+1=2]
(i) H2S2O7
(ii) XeF6
9. Calculate the degree of dissociation ( a) of acetic acid if its molar conductivity
( ?m) is 39.05 S cm
2
mol
?1
. [2]
Given ?
o
(H
+
) = 349.6 S cm
2
mol
?1
and ?
o
(CH3COO
?
) = 40.9 S cm
2
mol
?1
10. Write the equations involved in the following reactions: [2]
(i) Wolff-Kishner reduction
(ii) Etard reaction
11. A 10% solution (by mass) of sucrose in water has freezing point of 269.15 K
Calculate the freezing point of 10% glucose in water, if freezing point of pure
water is 273.15 K. [3]
Given: (Molar mass of sucrose = 342 g mol
?1
)
(Molar mass of glucose = 180 g mol
?1
)
12.
(a) Calculate the mass of Ag deposited at cathode when a current of 2 amperes was
passed through a solution of AgNO3 for 15 minutes. [2+1=3]
(Given: Molar mass of Ag = 108 g mol
?1
1F = 96500 C mol
?1
)
(b) Define fuel cell.
13.
i. What type of isomerism is shown by the complex [Co(NH3)6] [Cr(CN)6]?[1 ?3=3]
ii. Why a solution of [Ni(H2O)6]
2+
is green while a solution of [Ni(CN)4]
2 ?
is
colourless? (At. no. of Ni = 28)
iii. Write the IUPAC name of the following complex: [Co(NH3)5(CO3)]Cl
14. Write one difference in each of the following: [1 ?3=3]
(i) Lyophobic sol and Lyophilic sol
(ii) Solution and Colloid
(iii) Homogeneous catalysis and Heterogeneous catalysis
15. Following data are obtained for the reaction: [3]
N2O5 ? 2NO2 + ½ O2
t/s 0 300 600
[N2O5]/mol L
?1
1.6 ? 10
?2
0.8 ? 10
?2
0.4 ? 10
?2
CBSE XII | CHEMISTRY
Board Paper – 2017
(a) Show that it follows first order reaction.
(b) Calculate the half-life.
(Given log 2 = 0.3010, log 4 =0.6021)
16. Following compounds are given to you: [1 ?3=3]
2-Bromopentane, 2-Bmmo-2-methylbutane, 1-Bromopentane
(i) Write the compound which is most reactive towards SN2 reaction.
(ii) Write the compound which is optically active.
(iii) Write the compound which is most reactive towards ?-elimination reaction.
17.
(a) Write the principle of method used for the refining of germanium. [1 ?3=3]
(b) Out of PbS and PbCO3 (ores of lead), which one is concentrated by froth floatation
process preferably?
(c) What is the significance of leaching in the extraction of aluminium?
18. Write structures of compounds A, B and C in each of the following reactions :[
1
1
2
?2=3]
2(g) 5
3
2
3
(a)CO PCl Mg/dryether
65
(b)H O
(a)SnCl /HCl dil.NaOH
3
(b)H O
(i) C H Br A B C
(ii) CH CN A B C
?
?
?
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
OR
Do the following conversions in not more than two steps: [1 ?3=3]
(i) Benzoic acid to Benzaldehyde
(ii) Ethyl benzene to Benzoic acid
(iii) Propanone to Propene
19. Write the structures of the monomers used for getting the following polymers:[1 ?3=3]
(i) Dacron
(ii) Melamine –formaldehyde polymer
(iii) Buna –N
20. Define the following: [1 ?3=3]
(i) Anionic detergents
(ii) Broad spectrum antibiotics
(iii) Antiseptic
21. Given reasons: [1 ?3=3]
(i) Thermal stability decreases from H2O to H2Te.
(ii) Fluoride ion has higher hydration enthalpy than chloride ion.
(iii) Nitrogen does not form pentahalide.
Page 4
CBSE XII | CHEMISTRY
Board Paper – 2017
CBSE
Class XII Chemistry
Board Paper – 2017
Time: 3 Hours Total Marks: 70
General Instructions:
(i) All questions are compulsory.
(ii) Question numbers 1 to 5 are very short answer questions and carry 1 mark
each.
(iii) Question numbers 6 to 10 are short answer questions and carry 2 marks
each.
(iv) Question numbers 11 to 22 are also short answer questions and carry 3
marks each.
(v) Question number 23 is a value based question and carries 4 marks.
(vi) Question numbers 24 to 26 are long answer questions and carry 5 marks
each.
(vii) Use log tables, if necessary. Use of calculators is not allowed.
1. Write the formula of an oxo-anion of Manganese (Mn) in which it shows the
oxidation state equal to its group number. [1]
2. Write IUPAC name of the following compound-:
(CH3CH2)2NCH3 [1]
3. For a reaction R ? P, half-life (t1/2) is observed to be independent of the initial
concentration of reactants. What is the order of reaction? [1]
4. Write the structure of 1-Bromo-4-chlorobut-2-ene. [1]
5. Write one similarity between Physisorption and Chemisorption. [1]
6. Complete the following reactions: [1+1=2]
(i) NH3 + 3Cl2 (excess) ?
(ii) XeF6 + 2H2O ?
OR
What happens when
(i) (NH4)2Cr2O7 is heated?
(ii) H3PO3 is heated?
Write the equations.
7. Define the following terms: [1+1=2]
(i) Colligative properties
(ii) Molality (m)
CBSE XII | CHEMISTRY
Board Paper – 2017
8. Draw the structures of the following: [1+1=2]
(i) H2S2O7
(ii) XeF6
9. Calculate the degree of dissociation ( a) of acetic acid if its molar conductivity
( ?m) is 39.05 S cm
2
mol
?1
. [2]
Given ?
o
(H
+
) = 349.6 S cm
2
mol
?1
and ?
o
(CH3COO
?
) = 40.9 S cm
2
mol
?1
10. Write the equations involved in the following reactions: [2]
(i) Wolff-Kishner reduction
(ii) Etard reaction
11. A 10% solution (by mass) of sucrose in water has freezing point of 269.15 K
Calculate the freezing point of 10% glucose in water, if freezing point of pure
water is 273.15 K. [3]
Given: (Molar mass of sucrose = 342 g mol
?1
)
(Molar mass of glucose = 180 g mol
?1
)
12.
(a) Calculate the mass of Ag deposited at cathode when a current of 2 amperes was
passed through a solution of AgNO3 for 15 minutes. [2+1=3]
(Given: Molar mass of Ag = 108 g mol
?1
1F = 96500 C mol
?1
)
(b) Define fuel cell.
13.
i. What type of isomerism is shown by the complex [Co(NH3)6] [Cr(CN)6]?[1 ?3=3]
ii. Why a solution of [Ni(H2O)6]
2+
is green while a solution of [Ni(CN)4]
2 ?
is
colourless? (At. no. of Ni = 28)
iii. Write the IUPAC name of the following complex: [Co(NH3)5(CO3)]Cl
14. Write one difference in each of the following: [1 ?3=3]
(i) Lyophobic sol and Lyophilic sol
(ii) Solution and Colloid
(iii) Homogeneous catalysis and Heterogeneous catalysis
15. Following data are obtained for the reaction: [3]
N2O5 ? 2NO2 + ½ O2
t/s 0 300 600
[N2O5]/mol L
?1
1.6 ? 10
?2
0.8 ? 10
?2
0.4 ? 10
?2
CBSE XII | CHEMISTRY
Board Paper – 2017
(a) Show that it follows first order reaction.
(b) Calculate the half-life.
(Given log 2 = 0.3010, log 4 =0.6021)
16. Following compounds are given to you: [1 ?3=3]
2-Bromopentane, 2-Bmmo-2-methylbutane, 1-Bromopentane
(i) Write the compound which is most reactive towards SN2 reaction.
(ii) Write the compound which is optically active.
(iii) Write the compound which is most reactive towards ?-elimination reaction.
17.
(a) Write the principle of method used for the refining of germanium. [1 ?3=3]
(b) Out of PbS and PbCO3 (ores of lead), which one is concentrated by froth floatation
process preferably?
(c) What is the significance of leaching in the extraction of aluminium?
18. Write structures of compounds A, B and C in each of the following reactions :[
1
1
2
?2=3]
2(g) 5
3
2
3
(a)CO PCl Mg/dryether
65
(b)H O
(a)SnCl /HCl dil.NaOH
3
(b)H O
(i) C H Br A B C
(ii) CH CN A B C
?
?
?
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
OR
Do the following conversions in not more than two steps: [1 ?3=3]
(i) Benzoic acid to Benzaldehyde
(ii) Ethyl benzene to Benzoic acid
(iii) Propanone to Propene
19. Write the structures of the monomers used for getting the following polymers:[1 ?3=3]
(i) Dacron
(ii) Melamine –formaldehyde polymer
(iii) Buna –N
20. Define the following: [1 ?3=3]
(i) Anionic detergents
(ii) Broad spectrum antibiotics
(iii) Antiseptic
21. Given reasons: [1 ?3=3]
(i) Thermal stability decreases from H2O to H2Te.
(ii) Fluoride ion has higher hydration enthalpy than chloride ion.
(iii) Nitrogen does not form pentahalide.
CBSE XII | CHEMISTRY
Board Paper – 2017
22. Given reasons: [1 ?3=3]
(i) Acetylation of aniline reduces its activation effect.
(ii) CH3NH2 is more basic than C6H5NH2.
(iii) Although –NH2 is o/p directing group, yet aniline on nitration gives a significant
amount of m-nitroaniline.
23. After watching a programme on TV about the presence of carcinogens (cancer
causing agents) Potassium bromate and Potassium iodate in bread and other bakery
product, Ritu a class XII student decided to aware others about the adverse effects
of these carcinogens in foods. She consulted the school principal and requested him
to instruct canteen contractor to stop selling sandwiches, pizza, burgers and other
bakery products to the students. Principal took an immediate action and instructed
the canteen contractor to replace the bakery products with some proteins and
vitamins rich food like fruits, salads, sprouts etc. The decision was welcomed by the
parents and students. [4]
After reading the above passage, answer the following questions:
(i) What are the values (at least two) displayed by Ritu?
(ii) Which polysaccharide component of carbohydrates is commonly present
in bread?
(iii) Write the two types of secondary structure of proteins.
(iv) Give two examples of water soluble vitamins.
24.
(a) Account for the following: [3+2=5]
(i) Transition metals form large number of complex compounds.
(ii) The lowest oxide of transition metal is basic whereas the highest
oxide is amphoteric or acidic.
(iii) E
o
value for the Mn
3+
/Mn
2+
couple is highly positive (+1.57 V) as
compare to Cr
3+
/Cr
2+
.
(b) Write one similarity and one difference between the chemistry of
lanthanoid and actinoid elements.
OR
(a)
(i) How is the variability in oxidation states of transition metals different
from that of p-block elements?
(ii) Out of Cu
+
and Cu
2+
, which ion is unstable in aqueous solution and
why?
(iii) Orange colour of Cr2O7
2 ?
ion change to yellow when treated with an
alkali. Why?
(b) Chemistry of actinoids is complicated as compared to lanthanoids. Give two
reasons.
Page 5
CBSE XII | CHEMISTRY
Board Paper – 2017
CBSE
Class XII Chemistry
Board Paper – 2017
Time: 3 Hours Total Marks: 70
General Instructions:
(i) All questions are compulsory.
(ii) Question numbers 1 to 5 are very short answer questions and carry 1 mark
each.
(iii) Question numbers 6 to 10 are short answer questions and carry 2 marks
each.
(iv) Question numbers 11 to 22 are also short answer questions and carry 3
marks each.
(v) Question number 23 is a value based question and carries 4 marks.
(vi) Question numbers 24 to 26 are long answer questions and carry 5 marks
each.
(vii) Use log tables, if necessary. Use of calculators is not allowed.
1. Write the formula of an oxo-anion of Manganese (Mn) in which it shows the
oxidation state equal to its group number. [1]
2. Write IUPAC name of the following compound-:
(CH3CH2)2NCH3 [1]
3. For a reaction R ? P, half-life (t1/2) is observed to be independent of the initial
concentration of reactants. What is the order of reaction? [1]
4. Write the structure of 1-Bromo-4-chlorobut-2-ene. [1]
5. Write one similarity between Physisorption and Chemisorption. [1]
6. Complete the following reactions: [1+1=2]
(i) NH3 + 3Cl2 (excess) ?
(ii) XeF6 + 2H2O ?
OR
What happens when
(i) (NH4)2Cr2O7 is heated?
(ii) H3PO3 is heated?
Write the equations.
7. Define the following terms: [1+1=2]
(i) Colligative properties
(ii) Molality (m)
CBSE XII | CHEMISTRY
Board Paper – 2017
8. Draw the structures of the following: [1+1=2]
(i) H2S2O7
(ii) XeF6
9. Calculate the degree of dissociation ( a) of acetic acid if its molar conductivity
( ?m) is 39.05 S cm
2
mol
?1
. [2]
Given ?
o
(H
+
) = 349.6 S cm
2
mol
?1
and ?
o
(CH3COO
?
) = 40.9 S cm
2
mol
?1
10. Write the equations involved in the following reactions: [2]
(i) Wolff-Kishner reduction
(ii) Etard reaction
11. A 10% solution (by mass) of sucrose in water has freezing point of 269.15 K
Calculate the freezing point of 10% glucose in water, if freezing point of pure
water is 273.15 K. [3]
Given: (Molar mass of sucrose = 342 g mol
?1
)
(Molar mass of glucose = 180 g mol
?1
)
12.
(a) Calculate the mass of Ag deposited at cathode when a current of 2 amperes was
passed through a solution of AgNO3 for 15 minutes. [2+1=3]
(Given: Molar mass of Ag = 108 g mol
?1
1F = 96500 C mol
?1
)
(b) Define fuel cell.
13.
i. What type of isomerism is shown by the complex [Co(NH3)6] [Cr(CN)6]?[1 ?3=3]
ii. Why a solution of [Ni(H2O)6]
2+
is green while a solution of [Ni(CN)4]
2 ?
is
colourless? (At. no. of Ni = 28)
iii. Write the IUPAC name of the following complex: [Co(NH3)5(CO3)]Cl
14. Write one difference in each of the following: [1 ?3=3]
(i) Lyophobic sol and Lyophilic sol
(ii) Solution and Colloid
(iii) Homogeneous catalysis and Heterogeneous catalysis
15. Following data are obtained for the reaction: [3]
N2O5 ? 2NO2 + ½ O2
t/s 0 300 600
[N2O5]/mol L
?1
1.6 ? 10
?2
0.8 ? 10
?2
0.4 ? 10
?2
CBSE XII | CHEMISTRY
Board Paper – 2017
(a) Show that it follows first order reaction.
(b) Calculate the half-life.
(Given log 2 = 0.3010, log 4 =0.6021)
16. Following compounds are given to you: [1 ?3=3]
2-Bromopentane, 2-Bmmo-2-methylbutane, 1-Bromopentane
(i) Write the compound which is most reactive towards SN2 reaction.
(ii) Write the compound which is optically active.
(iii) Write the compound which is most reactive towards ?-elimination reaction.
17.
(a) Write the principle of method used for the refining of germanium. [1 ?3=3]
(b) Out of PbS and PbCO3 (ores of lead), which one is concentrated by froth floatation
process preferably?
(c) What is the significance of leaching in the extraction of aluminium?
18. Write structures of compounds A, B and C in each of the following reactions :[
1
1
2
?2=3]
2(g) 5
3
2
3
(a)CO PCl Mg/dryether
65
(b)H O
(a)SnCl /HCl dil.NaOH
3
(b)H O
(i) C H Br A B C
(ii) CH CN A B C
?
?
?
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
OR
Do the following conversions in not more than two steps: [1 ?3=3]
(i) Benzoic acid to Benzaldehyde
(ii) Ethyl benzene to Benzoic acid
(iii) Propanone to Propene
19. Write the structures of the monomers used for getting the following polymers:[1 ?3=3]
(i) Dacron
(ii) Melamine –formaldehyde polymer
(iii) Buna –N
20. Define the following: [1 ?3=3]
(i) Anionic detergents
(ii) Broad spectrum antibiotics
(iii) Antiseptic
21. Given reasons: [1 ?3=3]
(i) Thermal stability decreases from H2O to H2Te.
(ii) Fluoride ion has higher hydration enthalpy than chloride ion.
(iii) Nitrogen does not form pentahalide.
CBSE XII | CHEMISTRY
Board Paper – 2017
22. Given reasons: [1 ?3=3]
(i) Acetylation of aniline reduces its activation effect.
(ii) CH3NH2 is more basic than C6H5NH2.
(iii) Although –NH2 is o/p directing group, yet aniline on nitration gives a significant
amount of m-nitroaniline.
23. After watching a programme on TV about the presence of carcinogens (cancer
causing agents) Potassium bromate and Potassium iodate in bread and other bakery
product, Ritu a class XII student decided to aware others about the adverse effects
of these carcinogens in foods. She consulted the school principal and requested him
to instruct canteen contractor to stop selling sandwiches, pizza, burgers and other
bakery products to the students. Principal took an immediate action and instructed
the canteen contractor to replace the bakery products with some proteins and
vitamins rich food like fruits, salads, sprouts etc. The decision was welcomed by the
parents and students. [4]
After reading the above passage, answer the following questions:
(i) What are the values (at least two) displayed by Ritu?
(ii) Which polysaccharide component of carbohydrates is commonly present
in bread?
(iii) Write the two types of secondary structure of proteins.
(iv) Give two examples of water soluble vitamins.
24.
(a) Account for the following: [3+2=5]
(i) Transition metals form large number of complex compounds.
(ii) The lowest oxide of transition metal is basic whereas the highest
oxide is amphoteric or acidic.
(iii) E
o
value for the Mn
3+
/Mn
2+
couple is highly positive (+1.57 V) as
compare to Cr
3+
/Cr
2+
.
(b) Write one similarity and one difference between the chemistry of
lanthanoid and actinoid elements.
OR
(a)
(i) How is the variability in oxidation states of transition metals different
from that of p-block elements?
(ii) Out of Cu
+
and Cu
2+
, which ion is unstable in aqueous solution and
why?
(iii) Orange colour of Cr2O7
2 ?
ion change to yellow when treated with an
alkali. Why?
(b) Chemistry of actinoids is complicated as compared to lanthanoids. Give two
reasons.
CBSE XII | CHEMISTRY
Board Paper – 2017
25.
(a) An element has atomic mass 93 g mol
?1
and density 11.5 g cm
?3
. If the
edge length of its units cell is 300 pm, identify the type of unit cell. [3+2=5]
(b) Write any two differences between amorphous solids and crystalline solids.
OR
(a) Calculate the number of units cells in 8.1 g of aluminium if it crystallizes in a f.c.c.
structure. (Atomic mass of Al=27 g mol
?1
) [2+3=5]
(b) Give reasons:
(i) In stoichiometric defects, NaCl exhibits Schottky defect and not
Frenkel defect.
(ii) Silicon on doping with Phosphorus forms n-type semiconductor.
(iii) Ferrimagnetic substances show better magnetism than antiferromagnetic
substances.
26.
(a) Write the product (s) in the following reactions: [3+2=5]
(i)
(ii)
HI
3 2 3
CH CH O CH CH ? ?
CH
3
|
? ? ? ? ? ? ? ? ?
(iii)
PCC
32
CH CH CH CH OH ? ? ? ? ? ? ? ? ?
(b) Given simple chemical tests to distinguish between the following pairs of
compounds:
(i) Ethanol and Phenol
(ii) Propanol and 2-methylpropan-2-ol
OR
(a) Write the formula of reagents used in the following reactions:
(i) Bromination of phenol to 2, 4, 6-tribromophenol
(ii) Hydroborations of propene and then oxidation to propanol.
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FAQs on CBSE Chemistry Past year paper - 2017, Class 12 - Chemistry for Grade 12
| 1. What are the important topics to study for the CBSE Chemistry exam? |  |
Ans. The important topics to study for the CBSE Chemistry exam include chemical bonding, coordination compounds, biomolecules, polymers, and surface chemistry. These topics are frequently asked in the exam and have high weightage.
| 2. Can you provide some tips for scoring well in the CBSE Chemistry exam? | |
Ans. To score well in the CBSE Chemistry exam, it is important to understand the concepts thoroughly. Practice solving numerical problems and chemical equations regularly. Make sure to revise regularly and solve previous year question papers to get an idea of the exam pattern.
| 3. How can I improve my problem-solving skills in CBSE Chemistry? | |
Ans. To improve problem-solving skills in CBSE Chemistry, practice solving a variety of numerical problems from each chapter. Understand the concepts behind each problem and try to solve them step by step. Additionally, seek help from teachers or join study groups to clarify any doubts.
| 4. Are there any specific strategies to follow while writing answers in the CBSE Chemistry exam? | |
Ans. Yes, there are specific strategies to follow while writing answers in the CBSE Chemistry exam. Start by reading the question carefully and understand what is being asked. Structure your answer neatly and use appropriate chemical equations or diagrams wherever necessary. Write in a concise and clear manner, providing all the relevant information.
| 5. How can I manage my time effectively during the CBSE Chemistry exam? | |
Ans. To manage time effectively during the CBSE Chemistry exam, divide your time according to the marks allotted to each section. Start with the questions you are most confident about to save time. If you get stuck on a particular question, move on and come back to it later. Practice time management while solving previous year question papers to improve your speed.
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