CBSE Chemistry Past year paper - 2013, Class 12 Class 12 Notes | EduRev

Chemistry Class 12

Created by: Mohit Rajpoot

Class 12 : CBSE Chemistry Past year paper - 2013, Class 12 Class 12 Notes | EduRev

 Page 1


  
 
CBSE XII  |  Chemistry 
Board Paper - 2013 
 
     
CBSE 
Class XII Chemistry - Set 1 
Board Paper - 2013 
Time: 3 hours  Total Marks: 70 
 
General instructions: 
1. All questions are compulsory. 
2. Marks for each question are indicated against it. 
3. Question numbers 1 to 8 are very short- answer questions carrying1mark each. Answer 
these in one word or about one sentence each. 
4. Question numbers 9 to 18 are short-answer questions, carrying 2 marks each. Answer 
these in about 30 words each. 
5. Question numbers 19 to 27 are short answer questions, carrying 3 marks each. Answer 
these in about 40 words each. 
6. Question numbers 28 to 30 are long answer questions of carrying 5 marks each. Answer 
these in about 70 words each. 
7. Use Log Tables, if necessary. Use of calculators is not permitted. 
 
 
1.  How many atoms constitute one unit cell of a face-centered cubic crystal? [1] 
 
2.  Name the method used for the refining of Nickel metal. [1] 
 
3. 
 What is the covalency of nitrogen in N
2
O
5 
? 
[1] 
 
4. Write the IUPAC name of the  
3 2 2
CH CH CH CH CH
        |
        Cl
? ? ? ?
 
[1] 
5.  What happens when CH3Br is treated with KCN? [1] 
 
6. Write the structure of 3-methyl butanal. [1] 
 
7.  Arrange the following in increasing order of their basic strength in aqueous solution: 
          CH
3
NH
2
, (CH
3
)
3
N, (CH
3
)
2
NH 
[1] 
 
8. What are three types of RNA molecules which perform different functions? [1] 
 
9. 18 g of glucose, C6H12O6(Molar mass = 180 g mol
-1
) is dissolved in 1 kg of water in a sauce     
         pan. At what temperature will this solution boil? 
        (Kb for water = 0.52 k kg mol
-1
, boiling points of pure water =373.15K) [2] 
Page 2


  
 
CBSE XII  |  Chemistry 
Board Paper - 2013 
 
     
CBSE 
Class XII Chemistry - Set 1 
Board Paper - 2013 
Time: 3 hours  Total Marks: 70 
 
General instructions: 
1. All questions are compulsory. 
2. Marks for each question are indicated against it. 
3. Question numbers 1 to 8 are very short- answer questions carrying1mark each. Answer 
these in one word or about one sentence each. 
4. Question numbers 9 to 18 are short-answer questions, carrying 2 marks each. Answer 
these in about 30 words each. 
5. Question numbers 19 to 27 are short answer questions, carrying 3 marks each. Answer 
these in about 40 words each. 
6. Question numbers 28 to 30 are long answer questions of carrying 5 marks each. Answer 
these in about 70 words each. 
7. Use Log Tables, if necessary. Use of calculators is not permitted. 
 
 
1.  How many atoms constitute one unit cell of a face-centered cubic crystal? [1] 
 
2.  Name the method used for the refining of Nickel metal. [1] 
 
3. 
 What is the covalency of nitrogen in N
2
O
5 
? 
[1] 
 
4. Write the IUPAC name of the  
3 2 2
CH CH CH CH CH
        |
        Cl
? ? ? ?
 
[1] 
5.  What happens when CH3Br is treated with KCN? [1] 
 
6. Write the structure of 3-methyl butanal. [1] 
 
7.  Arrange the following in increasing order of their basic strength in aqueous solution: 
          CH
3
NH
2
, (CH
3
)
3
N, (CH
3
)
2
NH 
[1] 
 
8. What are three types of RNA molecules which perform different functions? [1] 
 
9. 18 g of glucose, C6H12O6(Molar mass = 180 g mol
-1
) is dissolved in 1 kg of water in a sauce     
         pan. At what temperature will this solution boil? 
        (Kb for water = 0.52 k kg mol
-1
, boiling points of pure water =373.15K) [2] 
  
 
CBSE XII  |  Chemistry 
Board Paper - 2013 
 
     
10. The conductivity of 0.20 M solution of KCl at 298 K is 0.025 S cm
-1
. Calculate its molar 
conductivity. [2] 
11. Write the dispersed phase and dispersion medium of the following colloidal systems: [2] 
(i) Smoke  
(ii) Milk 
OR 
 
What are lyophilic and lyophobic colloids? Which of these sols can be easily coagulated on 
the addition of small amounts of electrolytes? 
 
12.  Write the differences between physisorption and chemisorption with respect to the    
             following: [2] 
(i) Specificity 
(ii) Temperature dependence 
(iii) Reversibility and 
(iv) Enthalpy change 
 
13.  
(a) Which solution is used for the leaching of silver metal in the presence of air in the 
metallurgy of silver? 
(b) Out of C and CO, which is a better reducing agent at the lower temperature range in the 
blast furnace to extract iron from the oxide ore? [2] 
 
14. What happens when 
(i) PCl5 is heated? 
(ii) H3PO3 is heated? 
Write the reaction involved. [2] 
 
15.  
(a) Which metal in the first transition series (3d series) exhibits + 1 oxidation state most 
frequently and why? 
Which of the following cations are coloured in aqueous solutions and why? 
Sc
3+
, V
3+
, Ti
4+
,Mn
2+ 
(At. Nos. Sc = 21, V = 23, Ti = 22, Mn = 25) [2] 
 
16. Chlorobenzene is extremely less reactive towards a nucleophillic substitution reaction.  
Give two reasons for the same [2] 
 
17. Explain the mechanism of the following reaction. [2] 
? ? ? ? ?
+
H
3 2 3 2 2 3 2
413k
2CH -CH -OH CH CH -O-CH -CH +H O
 
 
  
Page 3


  
 
CBSE XII  |  Chemistry 
Board Paper - 2013 
 
     
CBSE 
Class XII Chemistry - Set 1 
Board Paper - 2013 
Time: 3 hours  Total Marks: 70 
 
General instructions: 
1. All questions are compulsory. 
2. Marks for each question are indicated against it. 
3. Question numbers 1 to 8 are very short- answer questions carrying1mark each. Answer 
these in one word or about one sentence each. 
4. Question numbers 9 to 18 are short-answer questions, carrying 2 marks each. Answer 
these in about 30 words each. 
5. Question numbers 19 to 27 are short answer questions, carrying 3 marks each. Answer 
these in about 40 words each. 
6. Question numbers 28 to 30 are long answer questions of carrying 5 marks each. Answer 
these in about 70 words each. 
7. Use Log Tables, if necessary. Use of calculators is not permitted. 
 
 
1.  How many atoms constitute one unit cell of a face-centered cubic crystal? [1] 
 
2.  Name the method used for the refining of Nickel metal. [1] 
 
3. 
 What is the covalency of nitrogen in N
2
O
5 
? 
[1] 
 
4. Write the IUPAC name of the  
3 2 2
CH CH CH CH CH
        |
        Cl
? ? ? ?
 
[1] 
5.  What happens when CH3Br is treated with KCN? [1] 
 
6. Write the structure of 3-methyl butanal. [1] 
 
7.  Arrange the following in increasing order of their basic strength in aqueous solution: 
          CH
3
NH
2
, (CH
3
)
3
N, (CH
3
)
2
NH 
[1] 
 
8. What are three types of RNA molecules which perform different functions? [1] 
 
9. 18 g of glucose, C6H12O6(Molar mass = 180 g mol
-1
) is dissolved in 1 kg of water in a sauce     
         pan. At what temperature will this solution boil? 
        (Kb for water = 0.52 k kg mol
-1
, boiling points of pure water =373.15K) [2] 
  
 
CBSE XII  |  Chemistry 
Board Paper - 2013 
 
     
10. The conductivity of 0.20 M solution of KCl at 298 K is 0.025 S cm
-1
. Calculate its molar 
conductivity. [2] 
11. Write the dispersed phase and dispersion medium of the following colloidal systems: [2] 
(i) Smoke  
(ii) Milk 
OR 
 
What are lyophilic and lyophobic colloids? Which of these sols can be easily coagulated on 
the addition of small amounts of electrolytes? 
 
12.  Write the differences between physisorption and chemisorption with respect to the    
             following: [2] 
(i) Specificity 
(ii) Temperature dependence 
(iii) Reversibility and 
(iv) Enthalpy change 
 
13.  
(a) Which solution is used for the leaching of silver metal in the presence of air in the 
metallurgy of silver? 
(b) Out of C and CO, which is a better reducing agent at the lower temperature range in the 
blast furnace to extract iron from the oxide ore? [2] 
 
14. What happens when 
(i) PCl5 is heated? 
(ii) H3PO3 is heated? 
Write the reaction involved. [2] 
 
15.  
(a) Which metal in the first transition series (3d series) exhibits + 1 oxidation state most 
frequently and why? 
Which of the following cations are coloured in aqueous solutions and why? 
Sc
3+
, V
3+
, Ti
4+
,Mn
2+ 
(At. Nos. Sc = 21, V = 23, Ti = 22, Mn = 25) [2] 
 
16. Chlorobenzene is extremely less reactive towards a nucleophillic substitution reaction.  
Give two reasons for the same [2] 
 
17. Explain the mechanism of the following reaction. [2] 
? ? ? ? ?
+
H
3 2 3 2 2 3 2
413k
2CH -CH -OH CH CH -O-CH -CH +H O
 
 
  
  
 
CBSE XII  |  Chemistry 
Board Paper - 2013 
 
     
18.  How will you convert: 
(i) Propene to Propan - 2-ol? 
(ii) Phenol to 2, 4,6-trinitrophenol? [2] 
 
19. After watching a programme on TV about the adverse effects of junk food and soft drinks  
on the health of school children, Sonali, a student of Class XII, discussed the issue with the 
school principal. Principal immediately instructed the canteen contractor to replace the 
fast food with the fibre and vitamins rich food like sprouts, salad, fruits etc. This decision 
was welcomed by the parents and the students. After reading the above passage, answer 
the following questions: 
(a) What values are expressed by Sonali and the Principal of the school? 
(b) Give two examples of water-soluble vitamins. [3] 
 
20.  How would you account for the following? 
(i) Transition metals exhibit variable oxidation states. 
(ii) Zr (Z = 40) and Hf (Z = 72) have almost identical radii. 
(iii) Transition metals and their compounds act as catalyst. 
 
OR 
Complete the following chemical equations: 
(i) 
22
27
Cr O 6Fe 14H
? ? ?
? ? ? 
(ii) 
2
4
2CrO 2H
??
?? 
(iii) 
2
4 2 4
2MnO 5C O 16H
? ? ?
? ? ?
 
[3]
 
 
21.  
(i) Which one of the following is a food preservative? 
Equanil, Morphine, Sodium benzoate 
(ii) Why is bithional added to soap? 
(iii) Which class of drugs is used in sleeping pills? [3] 
 
22.  
(a) What type of semiconductor is obtained when silicon is doped with boron? 
(b) What type of magnetism is shown in the following alignment of magnetic moments? 
(c) What type of point defect is produced when AgCl is dopedwithCdCl2? [3] 
 
23. Give the structures of products A, B and C in the following reactions: [3] 
(i) 
42
o
LiAlH HNO KCN
32
0C
CH CH Br A B C ? ?? ? ? ? ?? ? ? ? ?? ? ?  
(ii) 
33 2
NH CHCl AicKOH NaOH Br
3
CH COOH A B C
? ?
?
? ?? ? ? ? ?? ?? ? ? ? ?? ?? ?? ? 
Page 4


  
 
CBSE XII  |  Chemistry 
Board Paper - 2013 
 
     
CBSE 
Class XII Chemistry - Set 1 
Board Paper - 2013 
Time: 3 hours  Total Marks: 70 
 
General instructions: 
1. All questions are compulsory. 
2. Marks for each question are indicated against it. 
3. Question numbers 1 to 8 are very short- answer questions carrying1mark each. Answer 
these in one word or about one sentence each. 
4. Question numbers 9 to 18 are short-answer questions, carrying 2 marks each. Answer 
these in about 30 words each. 
5. Question numbers 19 to 27 are short answer questions, carrying 3 marks each. Answer 
these in about 40 words each. 
6. Question numbers 28 to 30 are long answer questions of carrying 5 marks each. Answer 
these in about 70 words each. 
7. Use Log Tables, if necessary. Use of calculators is not permitted. 
 
 
1.  How many atoms constitute one unit cell of a face-centered cubic crystal? [1] 
 
2.  Name the method used for the refining of Nickel metal. [1] 
 
3. 
 What is the covalency of nitrogen in N
2
O
5 
? 
[1] 
 
4. Write the IUPAC name of the  
3 2 2
CH CH CH CH CH
        |
        Cl
? ? ? ?
 
[1] 
5.  What happens when CH3Br is treated with KCN? [1] 
 
6. Write the structure of 3-methyl butanal. [1] 
 
7.  Arrange the following in increasing order of their basic strength in aqueous solution: 
          CH
3
NH
2
, (CH
3
)
3
N, (CH
3
)
2
NH 
[1] 
 
8. What are three types of RNA molecules which perform different functions? [1] 
 
9. 18 g of glucose, C6H12O6(Molar mass = 180 g mol
-1
) is dissolved in 1 kg of water in a sauce     
         pan. At what temperature will this solution boil? 
        (Kb for water = 0.52 k kg mol
-1
, boiling points of pure water =373.15K) [2] 
  
 
CBSE XII  |  Chemistry 
Board Paper - 2013 
 
     
10. The conductivity of 0.20 M solution of KCl at 298 K is 0.025 S cm
-1
. Calculate its molar 
conductivity. [2] 
11. Write the dispersed phase and dispersion medium of the following colloidal systems: [2] 
(i) Smoke  
(ii) Milk 
OR 
 
What are lyophilic and lyophobic colloids? Which of these sols can be easily coagulated on 
the addition of small amounts of electrolytes? 
 
12.  Write the differences between physisorption and chemisorption with respect to the    
             following: [2] 
(i) Specificity 
(ii) Temperature dependence 
(iii) Reversibility and 
(iv) Enthalpy change 
 
13.  
(a) Which solution is used for the leaching of silver metal in the presence of air in the 
metallurgy of silver? 
(b) Out of C and CO, which is a better reducing agent at the lower temperature range in the 
blast furnace to extract iron from the oxide ore? [2] 
 
14. What happens when 
(i) PCl5 is heated? 
(ii) H3PO3 is heated? 
Write the reaction involved. [2] 
 
15.  
(a) Which metal in the first transition series (3d series) exhibits + 1 oxidation state most 
frequently and why? 
Which of the following cations are coloured in aqueous solutions and why? 
Sc
3+
, V
3+
, Ti
4+
,Mn
2+ 
(At. Nos. Sc = 21, V = 23, Ti = 22, Mn = 25) [2] 
 
16. Chlorobenzene is extremely less reactive towards a nucleophillic substitution reaction.  
Give two reasons for the same [2] 
 
17. Explain the mechanism of the following reaction. [2] 
? ? ? ? ?
+
H
3 2 3 2 2 3 2
413k
2CH -CH -OH CH CH -O-CH -CH +H O
 
 
  
  
 
CBSE XII  |  Chemistry 
Board Paper - 2013 
 
     
18.  How will you convert: 
(i) Propene to Propan - 2-ol? 
(ii) Phenol to 2, 4,6-trinitrophenol? [2] 
 
19. After watching a programme on TV about the adverse effects of junk food and soft drinks  
on the health of school children, Sonali, a student of Class XII, discussed the issue with the 
school principal. Principal immediately instructed the canteen contractor to replace the 
fast food with the fibre and vitamins rich food like sprouts, salad, fruits etc. This decision 
was welcomed by the parents and the students. After reading the above passage, answer 
the following questions: 
(a) What values are expressed by Sonali and the Principal of the school? 
(b) Give two examples of water-soluble vitamins. [3] 
 
20.  How would you account for the following? 
(i) Transition metals exhibit variable oxidation states. 
(ii) Zr (Z = 40) and Hf (Z = 72) have almost identical radii. 
(iii) Transition metals and their compounds act as catalyst. 
 
OR 
Complete the following chemical equations: 
(i) 
22
27
Cr O 6Fe 14H
? ? ?
? ? ? 
(ii) 
2
4
2CrO 2H
??
?? 
(iii) 
2
4 2 4
2MnO 5C O 16H
? ? ?
? ? ?
 
[3]
 
 
21.  
(i) Which one of the following is a food preservative? 
Equanil, Morphine, Sodium benzoate 
(ii) Why is bithional added to soap? 
(iii) Which class of drugs is used in sleeping pills? [3] 
 
22.  
(a) What type of semiconductor is obtained when silicon is doped with boron? 
(b) What type of magnetism is shown in the following alignment of magnetic moments? 
(c) What type of point defect is produced when AgCl is dopedwithCdCl2? [3] 
 
23. Give the structures of products A, B and C in the following reactions: [3] 
(i) 
42
o
LiAlH HNO KCN
32
0C
CH CH Br A B C ? ?? ? ? ? ?? ? ? ? ?? ? ?  
(ii) 
33 2
NH CHCl AicKOH NaOH Br
3
CH COOH A B C
? ?
?
? ?? ? ? ? ?? ?? ? ? ? ?? ?? ?? ? 
  
 
CBSE XII  |  Chemistry 
Board Paper - 2013 
 
     
 
 
 
24. Write the IUPAC names of the following coordination compounds: 
(i) [Cr(NH3)3Cl3] 
(ii) K3[Fe(CN)6] 
(iii) [CoBr2(en)2]
+
, (en=ethylenediamine) [3] 
 
25. Determine the osmotic pressure of a solution prepared by dissolving 2.5 × 10
–2 
g of   
K2SO4 in 2L of water at 25°C, assuming that it is completely dissociated. 
(R = 0.0821 L atm K –1 mol –1, Molar mass of K2SO4 = 174gmol
–1
) [3] 
 
26. Calculate the emf of the following cell at 298 K:  
Fe(s) | Fe
2+ 
(0.001M)|| H+(1M) | H2(g) (1bar), Pt(s) 
(Given E°cell =+0.44V) [3] 
 
27. Write the names and structures of the monomers of the following polymers: [3] 
(i) (i)Bakelite 
(ii) Nylon-6 
(iii) Polythene 
 
28.  
(a) Give reasons for the following: 
(i) Bond enthalpy of F2 is lower than that of Cl2. 
(ii) PH3 has lower boiling point than NH3. 
(b) Draw the structures of the following molecules: 
(i) BrF3 
(ii) (HPO3)3 
(iii) XeF4 
OR 
 
(a) Account for the following:  
(i) Helium is used in diving apparatus. 
(ii) Fluorine does not exhibit positive oxidation state. 
(iii) Oxygen shows catenation behavior less than sulphur. 
 
(b) Draw the structures of the following molecules: 
(i) XeF2 
(ii) H2S2O8 [5] 
 
  
Page 5


  
 
CBSE XII  |  Chemistry 
Board Paper - 2013 
 
     
CBSE 
Class XII Chemistry - Set 1 
Board Paper - 2013 
Time: 3 hours  Total Marks: 70 
 
General instructions: 
1. All questions are compulsory. 
2. Marks for each question are indicated against it. 
3. Question numbers 1 to 8 are very short- answer questions carrying1mark each. Answer 
these in one word or about one sentence each. 
4. Question numbers 9 to 18 are short-answer questions, carrying 2 marks each. Answer 
these in about 30 words each. 
5. Question numbers 19 to 27 are short answer questions, carrying 3 marks each. Answer 
these in about 40 words each. 
6. Question numbers 28 to 30 are long answer questions of carrying 5 marks each. Answer 
these in about 70 words each. 
7. Use Log Tables, if necessary. Use of calculators is not permitted. 
 
 
1.  How many atoms constitute one unit cell of a face-centered cubic crystal? [1] 
 
2.  Name the method used for the refining of Nickel metal. [1] 
 
3. 
 What is the covalency of nitrogen in N
2
O
5 
? 
[1] 
 
4. Write the IUPAC name of the  
3 2 2
CH CH CH CH CH
        |
        Cl
? ? ? ?
 
[1] 
5.  What happens when CH3Br is treated with KCN? [1] 
 
6. Write the structure of 3-methyl butanal. [1] 
 
7.  Arrange the following in increasing order of their basic strength in aqueous solution: 
          CH
3
NH
2
, (CH
3
)
3
N, (CH
3
)
2
NH 
[1] 
 
8. What are three types of RNA molecules which perform different functions? [1] 
 
9. 18 g of glucose, C6H12O6(Molar mass = 180 g mol
-1
) is dissolved in 1 kg of water in a sauce     
         pan. At what temperature will this solution boil? 
        (Kb for water = 0.52 k kg mol
-1
, boiling points of pure water =373.15K) [2] 
  
 
CBSE XII  |  Chemistry 
Board Paper - 2013 
 
     
10. The conductivity of 0.20 M solution of KCl at 298 K is 0.025 S cm
-1
. Calculate its molar 
conductivity. [2] 
11. Write the dispersed phase and dispersion medium of the following colloidal systems: [2] 
(i) Smoke  
(ii) Milk 
OR 
 
What are lyophilic and lyophobic colloids? Which of these sols can be easily coagulated on 
the addition of small amounts of electrolytes? 
 
12.  Write the differences between physisorption and chemisorption with respect to the    
             following: [2] 
(i) Specificity 
(ii) Temperature dependence 
(iii) Reversibility and 
(iv) Enthalpy change 
 
13.  
(a) Which solution is used for the leaching of silver metal in the presence of air in the 
metallurgy of silver? 
(b) Out of C and CO, which is a better reducing agent at the lower temperature range in the 
blast furnace to extract iron from the oxide ore? [2] 
 
14. What happens when 
(i) PCl5 is heated? 
(ii) H3PO3 is heated? 
Write the reaction involved. [2] 
 
15.  
(a) Which metal in the first transition series (3d series) exhibits + 1 oxidation state most 
frequently and why? 
Which of the following cations are coloured in aqueous solutions and why? 
Sc
3+
, V
3+
, Ti
4+
,Mn
2+ 
(At. Nos. Sc = 21, V = 23, Ti = 22, Mn = 25) [2] 
 
16. Chlorobenzene is extremely less reactive towards a nucleophillic substitution reaction.  
Give two reasons for the same [2] 
 
17. Explain the mechanism of the following reaction. [2] 
? ? ? ? ?
+
H
3 2 3 2 2 3 2
413k
2CH -CH -OH CH CH -O-CH -CH +H O
 
 
  
  
 
CBSE XII  |  Chemistry 
Board Paper - 2013 
 
     
18.  How will you convert: 
(i) Propene to Propan - 2-ol? 
(ii) Phenol to 2, 4,6-trinitrophenol? [2] 
 
19. After watching a programme on TV about the adverse effects of junk food and soft drinks  
on the health of school children, Sonali, a student of Class XII, discussed the issue with the 
school principal. Principal immediately instructed the canteen contractor to replace the 
fast food with the fibre and vitamins rich food like sprouts, salad, fruits etc. This decision 
was welcomed by the parents and the students. After reading the above passage, answer 
the following questions: 
(a) What values are expressed by Sonali and the Principal of the school? 
(b) Give two examples of water-soluble vitamins. [3] 
 
20.  How would you account for the following? 
(i) Transition metals exhibit variable oxidation states. 
(ii) Zr (Z = 40) and Hf (Z = 72) have almost identical radii. 
(iii) Transition metals and their compounds act as catalyst. 
 
OR 
Complete the following chemical equations: 
(i) 
22
27
Cr O 6Fe 14H
? ? ?
? ? ? 
(ii) 
2
4
2CrO 2H
??
?? 
(iii) 
2
4 2 4
2MnO 5C O 16H
? ? ?
? ? ?
 
[3]
 
 
21.  
(i) Which one of the following is a food preservative? 
Equanil, Morphine, Sodium benzoate 
(ii) Why is bithional added to soap? 
(iii) Which class of drugs is used in sleeping pills? [3] 
 
22.  
(a) What type of semiconductor is obtained when silicon is doped with boron? 
(b) What type of magnetism is shown in the following alignment of magnetic moments? 
(c) What type of point defect is produced when AgCl is dopedwithCdCl2? [3] 
 
23. Give the structures of products A, B and C in the following reactions: [3] 
(i) 
42
o
LiAlH HNO KCN
32
0C
CH CH Br A B C ? ?? ? ? ? ?? ? ? ? ?? ? ?  
(ii) 
33 2
NH CHCl AicKOH NaOH Br
3
CH COOH A B C
? ?
?
? ?? ? ? ? ?? ?? ? ? ? ?? ?? ?? ? 
  
 
CBSE XII  |  Chemistry 
Board Paper - 2013 
 
     
 
 
 
24. Write the IUPAC names of the following coordination compounds: 
(i) [Cr(NH3)3Cl3] 
(ii) K3[Fe(CN)6] 
(iii) [CoBr2(en)2]
+
, (en=ethylenediamine) [3] 
 
25. Determine the osmotic pressure of a solution prepared by dissolving 2.5 × 10
–2 
g of   
K2SO4 in 2L of water at 25°C, assuming that it is completely dissociated. 
(R = 0.0821 L atm K –1 mol –1, Molar mass of K2SO4 = 174gmol
–1
) [3] 
 
26. Calculate the emf of the following cell at 298 K:  
Fe(s) | Fe
2+ 
(0.001M)|| H+(1M) | H2(g) (1bar), Pt(s) 
(Given E°cell =+0.44V) [3] 
 
27. Write the names and structures of the monomers of the following polymers: [3] 
(i) (i)Bakelite 
(ii) Nylon-6 
(iii) Polythene 
 
28.  
(a) Give reasons for the following: 
(i) Bond enthalpy of F2 is lower than that of Cl2. 
(ii) PH3 has lower boiling point than NH3. 
(b) Draw the structures of the following molecules: 
(i) BrF3 
(ii) (HPO3)3 
(iii) XeF4 
OR 
 
(a) Account for the following:  
(i) Helium is used in diving apparatus. 
(ii) Fluorine does not exhibit positive oxidation state. 
(iii) Oxygen shows catenation behavior less than sulphur. 
 
(b) Draw the structures of the following molecules: 
(i) XeF2 
(ii) H2S2O8 [5] 
 
  
  
 
CBSE XII  |  Chemistry 
Board Paper - 2013 
 
     
29.  
(a) Although phenoxide ion has more number of resonating structures than Carboxylate 
ion, Carboxylic acid is a stronger acid than phenol. Give two reasons. 
(b) How will you bring about the following conversions? 
(i) Propanone to propane 
(ii) Benzoyl chloride to benzaldehyde 
(iii) Ethanal to but-2-enal 
 
OR 
 
(a) Complete the following reactions: 
 
(b) Give simple chemical tests to distinguish between the following pairs of compounds:  
(i) Ethanal and Propanal 
(ii) Benzoic acid and Phenol 
30.  
(a) 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? 
(iii) How is the rate affected when the concentrations of both A and B are doubled? 
 
(b) A first order reaction takes 40 minutes for 30% decomposition. Calculate t1/2 for this 
reaction. (Given log 1.428 =0.1548) 
 
OR 
 
(a) For a first order reaction, show that time required for 99% completion is twice the time 
required for the completion of 90% of reaction. 
(b) Rate constant 'k' of a reaction varies with temperature 'T' according to the equation: 
Ea 1
logK=log A-
2.303R T
??
??
??
 
Where Ea is the activation energy. When a graph is plotted for log k Vs
1
T
??
??
??
,a straight 
line with a slope of –4250 K is obtained. Calculate 'Ea' for the reaction. 
(R = 8.314 JK
–1 
mol-
1
) 
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