CBSE Chemistry Past year paper - 2019, Class 12 | Chemistry for Grade 12 PDF Download

 Page 1


  
 
CBSE XII  | CHEMISTRY 
Board Paper – 2019 (SET-3) 
 
     
CBSE 
Class XII Chemistry 
Board Paper – 2019 
 
Time: 3 Hours  Total Marks: 70                                                                           
  
General Instructions:    
? All questions are compulsory. 
? Section A: Questions numbers 1 to 5 are very short answer questions and carry 1 
mark each. 
? Section B: Questions numbers 6 to 12 are short answer questions and carry 2 
marks each. 
? Section C: Questions numbers 13 to 24 are also short answer questions and carry 3 
marks each. 
? Section D: Questions numbers 25 In 27 are long answer questions and carry 5 
marks each. 
? There is no overall choice. However, an internal choice has been provided in two 
questions of one mark, two questions of two marks, four questions of three marks 
and all the three questions of five marks weightage. You have to attempt only one 
of the choices in such questions. 
? Use log tables if necessary. Use of a calculator is not allowed. 
 
 
SECTION A 
1. Write the IUPAC name of the following compound:  [1] 
 
 
2. Why is chloroform kept in dark-coloured bottles?  [1] 
 
 
3. Write the IUPAC name of the complex 
? ?
2
2
Co en Cl
?
??
??
  [1] 
OR 
Using IUPAC norms, write the formula of sodium tetrachloridonickelate(II). 
  
 
4. What is the difference between a glycosidic linkage and a peptide linkage?  [1] 
 
OR 
What is the difference between Nucleotide and Nucleoside? 
 
5. Arrange the following in the increasing order of their acidic character:  [1] 
Ethanol, Phenol, Water 
 
Page 2


  
 
CBSE XII  | CHEMISTRY 
Board Paper – 2019 (SET-3) 
 
     
CBSE 
Class XII Chemistry 
Board Paper – 2019 
 
Time: 3 Hours  Total Marks: 70                                                                           
  
General Instructions:    
? All questions are compulsory. 
? Section A: Questions numbers 1 to 5 are very short answer questions and carry 1 
mark each. 
? Section B: Questions numbers 6 to 12 are short answer questions and carry 2 
marks each. 
? Section C: Questions numbers 13 to 24 are also short answer questions and carry 3 
marks each. 
? Section D: Questions numbers 25 In 27 are long answer questions and carry 5 
marks each. 
? There is no overall choice. However, an internal choice has been provided in two 
questions of one mark, two questions of two marks, four questions of three marks 
and all the three questions of five marks weightage. You have to attempt only one 
of the choices in such questions. 
? Use log tables if necessary. Use of a calculator is not allowed. 
 
 
SECTION A 
1. Write the IUPAC name of the following compound:  [1] 
 
 
2. Why is chloroform kept in dark-coloured bottles?  [1] 
 
 
3. Write the IUPAC name of the complex 
? ?
2
2
Co en Cl
?
??
??
  [1] 
OR 
Using IUPAC norms, write the formula of sodium tetrachloridonickelate(II). 
  
 
4. What is the difference between a glycosidic linkage and a peptide linkage?  [1] 
 
OR 
What is the difference between Nucleotide and Nucleoside? 
 
5. Arrange the following in the increasing order of their acidic character:  [1] 
Ethanol, Phenol, Water 
 
  
 
CBSE XII  | CHEMISTRY 
Board Paper – 2019 (SET-3) 
 
     
 
SECTION B 
6.   [2] 
(a) Out of 0.1 molal aqueous solution of glucose and 0.1 molal aqueous 
solution of  KCl, which one will have higher boiling point and why? 
(b) Predict whether van’t Hoff factor(i) is less than one or greater than one in 
the following: 
(i) CH
3
COOH dissolved in water 
(ii) CH
3
COOH dissolved in benzene 
 
7. What happens when AgCl is doped with CdCl
2
? What is the name of this defect?     
 [2] 
OR 
What type of defect is shown by NaCl in 
(a) Stoichiometric defects 
(b) Non-stoichiometric defects 
 
8. Complete and balance the following equations:  [2] 
(a) NH
3
 (excess) + Cl
2
  
(b) XeF
6
 + 2H
2
O  
 
9. Write any two oxoacids of sulphur and draw their structures.  [2] 
 
 
10. Write the name of two fuels other than hydrogen used in a fuel cell. Write two 
advantages of a fuel cell over an ordinary cell.  [2] 
 
11. Write the structures of compounds A and B in each of the following reactions: [2] 
(a)  
 
 
(b)  
   
 
12.  Account for the following:  [2] 
(a) Gabriel phthalimide synthesis is not preferred for preparing aromatic 
primary amines. 
 
Page 3


  
 
CBSE XII  | CHEMISTRY 
Board Paper – 2019 (SET-3) 
 
     
CBSE 
Class XII Chemistry 
Board Paper – 2019 
 
Time: 3 Hours  Total Marks: 70                                                                           
  
General Instructions:    
? All questions are compulsory. 
? Section A: Questions numbers 1 to 5 are very short answer questions and carry 1 
mark each. 
? Section B: Questions numbers 6 to 12 are short answer questions and carry 2 
marks each. 
? Section C: Questions numbers 13 to 24 are also short answer questions and carry 3 
marks each. 
? Section D: Questions numbers 25 In 27 are long answer questions and carry 5 
marks each. 
? There is no overall choice. However, an internal choice has been provided in two 
questions of one mark, two questions of two marks, four questions of three marks 
and all the three questions of five marks weightage. You have to attempt only one 
of the choices in such questions. 
? Use log tables if necessary. Use of a calculator is not allowed. 
 
 
SECTION A 
1. Write the IUPAC name of the following compound:  [1] 
 
 
2. Why is chloroform kept in dark-coloured bottles?  [1] 
 
 
3. Write the IUPAC name of the complex 
? ?
2
2
Co en Cl
?
??
??
  [1] 
OR 
Using IUPAC norms, write the formula of sodium tetrachloridonickelate(II). 
  
 
4. What is the difference between a glycosidic linkage and a peptide linkage?  [1] 
 
OR 
What is the difference between Nucleotide and Nucleoside? 
 
5. Arrange the following in the increasing order of their acidic character:  [1] 
Ethanol, Phenol, Water 
 
  
 
CBSE XII  | CHEMISTRY 
Board Paper – 2019 (SET-3) 
 
     
 
SECTION B 
6.   [2] 
(a) Out of 0.1 molal aqueous solution of glucose and 0.1 molal aqueous 
solution of  KCl, which one will have higher boiling point and why? 
(b) Predict whether van’t Hoff factor(i) is less than one or greater than one in 
the following: 
(i) CH
3
COOH dissolved in water 
(ii) CH
3
COOH dissolved in benzene 
 
7. What happens when AgCl is doped with CdCl
2
? What is the name of this defect?     
 [2] 
OR 
What type of defect is shown by NaCl in 
(a) Stoichiometric defects 
(b) Non-stoichiometric defects 
 
8. Complete and balance the following equations:  [2] 
(a) NH
3
 (excess) + Cl
2
  
(b) XeF
6
 + 2H
2
O  
 
9. Write any two oxoacids of sulphur and draw their structures.  [2] 
 
 
10. Write the name of two fuels other than hydrogen used in a fuel cell. Write two 
advantages of a fuel cell over an ordinary cell.  [2] 
 
11. Write the structures of compounds A and B in each of the following reactions: [2] 
(a)  
 
 
(b)  
   
 
12.  Account for the following:  [2] 
(a) Gabriel phthalimide synthesis is not preferred for preparing aromatic 
primary amines. 
 
  
 
CBSE XII  | CHEMISTRY 
Board Paper – 2019 (SET-3) 
 
     
(b) On reaction with benzene sulphonyl chloride, the primary amine yields a 
product soluble in alkali, whereas the secondary amine yields a product 
insoluble in alkali. 
 
SECTION C 
 
13.  [3] 
(a) Following reaction takes place in the cell: 
      Zn
(s)
 + Ag
2
O
(s)
 + H
2
O
(l)
 ? Zn
2+
(aq)
 + 2Ag
(s)
 + 2OH
– (aq)
 
      Calculate ?
r
G° of the reaction. 
      [Given E°
(Zn2+/Zn)
  = -0.76V, E°
(Ag
+
/Ag)
 = 0.80 V, 1 F = 96,600 C mol
-1
] 
 
(b) How can you determine limiting molar conductivity 
? ?
m
? for a strong 
electrolyte and a weak electrolyte? 
 
14. Define the following with a suitable example of each:  [3] 
(a) Coagulation 
(b) Multimolecular colloid 
(c) Gel 
OR 
(a) Out of starch and ferric hydroxide sol, which one can easily be coagulated 
and why? 
(b) What is observed when an emulsion is centrifuged? 
(c) What is the role of promoters and poisons in catalysis? 
 
 
15.   [3] 
(a) An element crystallises in a bcc lattice with a cell edge of 3 × 10
-8
 cm. The 
density of the element is 6.89 g cm
-3
. Calculate the molar mass of the 
element (N
A
 = 6.022 × 10
23
 mol
-1
). 
(b) What type of semiconductor is obtained when 
(i) Ge is doped with In 
(ii) Si is doped with P 
 
16. A 0.1 M solution of Na
2
SO
4
 is dissolved to the extent of 95%. What would be 
its osmotic pressure at 27°C? (R = 0.0821 L atm K
-1
mol
-1
)  [3] 
 
17. Write down the reactions taking place in a blast furnace related to the 
metallurgy of iron in the temperature range 500–800 K. What is the role of 
limestone in the metallurgy of iron?  [3] 
 
OR 
What happens when 
(a) Silver is leached with NaCN in the presence of air? 
Page 4


  
 
CBSE XII  | CHEMISTRY 
Board Paper – 2019 (SET-3) 
 
     
CBSE 
Class XII Chemistry 
Board Paper – 2019 
 
Time: 3 Hours  Total Marks: 70                                                                           
  
General Instructions:    
? All questions are compulsory. 
? Section A: Questions numbers 1 to 5 are very short answer questions and carry 1 
mark each. 
? Section B: Questions numbers 6 to 12 are short answer questions and carry 2 
marks each. 
? Section C: Questions numbers 13 to 24 are also short answer questions and carry 3 
marks each. 
? Section D: Questions numbers 25 In 27 are long answer questions and carry 5 
marks each. 
? There is no overall choice. However, an internal choice has been provided in two 
questions of one mark, two questions of two marks, four questions of three marks 
and all the three questions of five marks weightage. You have to attempt only one 
of the choices in such questions. 
? Use log tables if necessary. Use of a calculator is not allowed. 
 
 
SECTION A 
1. Write the IUPAC name of the following compound:  [1] 
 
 
2. Why is chloroform kept in dark-coloured bottles?  [1] 
 
 
3. Write the IUPAC name of the complex 
? ?
2
2
Co en Cl
?
??
??
  [1] 
OR 
Using IUPAC norms, write the formula of sodium tetrachloridonickelate(II). 
  
 
4. What is the difference between a glycosidic linkage and a peptide linkage?  [1] 
 
OR 
What is the difference between Nucleotide and Nucleoside? 
 
5. Arrange the following in the increasing order of their acidic character:  [1] 
Ethanol, Phenol, Water 
 
  
 
CBSE XII  | CHEMISTRY 
Board Paper – 2019 (SET-3) 
 
     
 
SECTION B 
6.   [2] 
(a) Out of 0.1 molal aqueous solution of glucose and 0.1 molal aqueous 
solution of  KCl, which one will have higher boiling point and why? 
(b) Predict whether van’t Hoff factor(i) is less than one or greater than one in 
the following: 
(i) CH
3
COOH dissolved in water 
(ii) CH
3
COOH dissolved in benzene 
 
7. What happens when AgCl is doped with CdCl
2
? What is the name of this defect?     
 [2] 
OR 
What type of defect is shown by NaCl in 
(a) Stoichiometric defects 
(b) Non-stoichiometric defects 
 
8. Complete and balance the following equations:  [2] 
(a) NH
3
 (excess) + Cl
2
  
(b) XeF
6
 + 2H
2
O  
 
9. Write any two oxoacids of sulphur and draw their structures.  [2] 
 
 
10. Write the name of two fuels other than hydrogen used in a fuel cell. Write two 
advantages of a fuel cell over an ordinary cell.  [2] 
 
11. Write the structures of compounds A and B in each of the following reactions: [2] 
(a)  
 
 
(b)  
   
 
12.  Account for the following:  [2] 
(a) Gabriel phthalimide synthesis is not preferred for preparing aromatic 
primary amines. 
 
  
 
CBSE XII  | CHEMISTRY 
Board Paper – 2019 (SET-3) 
 
     
(b) On reaction with benzene sulphonyl chloride, the primary amine yields a 
product soluble in alkali, whereas the secondary amine yields a product 
insoluble in alkali. 
 
SECTION C 
 
13.  [3] 
(a) Following reaction takes place in the cell: 
      Zn
(s)
 + Ag
2
O
(s)
 + H
2
O
(l)
 ? Zn
2+
(aq)
 + 2Ag
(s)
 + 2OH
– (aq)
 
      Calculate ?
r
G° of the reaction. 
      [Given E°
(Zn2+/Zn)
  = -0.76V, E°
(Ag
+
/Ag)
 = 0.80 V, 1 F = 96,600 C mol
-1
] 
 
(b) How can you determine limiting molar conductivity 
? ?
m
? for a strong 
electrolyte and a weak electrolyte? 
 
14. Define the following with a suitable example of each:  [3] 
(a) Coagulation 
(b) Multimolecular colloid 
(c) Gel 
OR 
(a) Out of starch and ferric hydroxide sol, which one can easily be coagulated 
and why? 
(b) What is observed when an emulsion is centrifuged? 
(c) What is the role of promoters and poisons in catalysis? 
 
 
15.   [3] 
(a) An element crystallises in a bcc lattice with a cell edge of 3 × 10
-8
 cm. The 
density of the element is 6.89 g cm
-3
. Calculate the molar mass of the 
element (N
A
 = 6.022 × 10
23
 mol
-1
). 
(b) What type of semiconductor is obtained when 
(i) Ge is doped with In 
(ii) Si is doped with P 
 
16. A 0.1 M solution of Na
2
SO
4
 is dissolved to the extent of 95%. What would be 
its osmotic pressure at 27°C? (R = 0.0821 L atm K
-1
mol
-1
)  [3] 
 
17. Write down the reactions taking place in a blast furnace related to the 
metallurgy of iron in the temperature range 500–800 K. What is the role of 
limestone in the metallurgy of iron?  [3] 
 
OR 
What happens when 
(a) Silver is leached with NaCN in the presence of air? 
  
 
CBSE XII  | CHEMISTRY 
Board Paper – 2019 (SET-3) 
 
     
(b) Copper matte is charged into a silica-lined converter and a hot air blast is 
blown? 
(c) NaCN is added in an ore containing PbS and ZnS during concentration by 
the froth flotation method? 
 
 
18.  Give reasons for the following: [3] 
(a) Acidic character decreases from N
2
O
3
 to Bi
2
O
3
. 
(b) All the P–Cl bonds in PCl
5
 are not equivalent. 
(c) HF is a weaker acid than HCl in an aqueous solution. 
 
19. Write the structures of monomers used to obtain the following polymers : [3] 
(a) Natural rubber 
(b) PVC 
(c) Nylon-6.6 
 
OR 
Write the mechanism of free radical polymerisation of ethane. 
 
20.   [3] 
(a) Why are metal hydroxides a better alternative than sodium hydrogen 
carbonate in antacids? 
(b) Why is aspirin used in the prevention of heart attacks? 
(c) Why do antihistamines not affect the secretion of acid in the stomach? 
 
OR 
Define the following terms with a suitable example of each: 
(a) Tranquillisers 
(b) Antibiotics 
(c) Non-ionic detergents 
 
 
21.  [3] 
(a) Out of  and , which one is more reactive towards the 
S
N
2 reaction and why?  
(b) Out of  and , which one is more reactive towards the 
nucleophilic substitution reaction and why?  
(c) Out of  and , which one is optically active and why? 
 
 
22. What happens when  [3] 
Page 5


  
 
CBSE XII  | CHEMISTRY 
Board Paper – 2019 (SET-3) 
 
     
CBSE 
Class XII Chemistry 
Board Paper – 2019 
 
Time: 3 Hours  Total Marks: 70                                                                           
  
General Instructions:    
? All questions are compulsory. 
? Section A: Questions numbers 1 to 5 are very short answer questions and carry 1 
mark each. 
? Section B: Questions numbers 6 to 12 are short answer questions and carry 2 
marks each. 
? Section C: Questions numbers 13 to 24 are also short answer questions and carry 3 
marks each. 
? Section D: Questions numbers 25 In 27 are long answer questions and carry 5 
marks each. 
? There is no overall choice. However, an internal choice has been provided in two 
questions of one mark, two questions of two marks, four questions of three marks 
and all the three questions of five marks weightage. You have to attempt only one 
of the choices in such questions. 
? Use log tables if necessary. Use of a calculator is not allowed. 
 
 
SECTION A 
1. Write the IUPAC name of the following compound:  [1] 
 
 
2. Why is chloroform kept in dark-coloured bottles?  [1] 
 
 
3. Write the IUPAC name of the complex 
? ?
2
2
Co en Cl
?
??
??
  [1] 
OR 
Using IUPAC norms, write the formula of sodium tetrachloridonickelate(II). 
  
 
4. What is the difference between a glycosidic linkage and a peptide linkage?  [1] 
 
OR 
What is the difference between Nucleotide and Nucleoside? 
 
5. Arrange the following in the increasing order of their acidic character:  [1] 
Ethanol, Phenol, Water 
 
  
 
CBSE XII  | CHEMISTRY 
Board Paper – 2019 (SET-3) 
 
     
 
SECTION B 
6.   [2] 
(a) Out of 0.1 molal aqueous solution of glucose and 0.1 molal aqueous 
solution of  KCl, which one will have higher boiling point and why? 
(b) Predict whether van’t Hoff factor(i) is less than one or greater than one in 
the following: 
(i) CH
3
COOH dissolved in water 
(ii) CH
3
COOH dissolved in benzene 
 
7. What happens when AgCl is doped with CdCl
2
? What is the name of this defect?     
 [2] 
OR 
What type of defect is shown by NaCl in 
(a) Stoichiometric defects 
(b) Non-stoichiometric defects 
 
8. Complete and balance the following equations:  [2] 
(a) NH
3
 (excess) + Cl
2
  
(b) XeF
6
 + 2H
2
O  
 
9. Write any two oxoacids of sulphur and draw their structures.  [2] 
 
 
10. Write the name of two fuels other than hydrogen used in a fuel cell. Write two 
advantages of a fuel cell over an ordinary cell.  [2] 
 
11. Write the structures of compounds A and B in each of the following reactions: [2] 
(a)  
 
 
(b)  
   
 
12.  Account for the following:  [2] 
(a) Gabriel phthalimide synthesis is not preferred for preparing aromatic 
primary amines. 
 
  
 
CBSE XII  | CHEMISTRY 
Board Paper – 2019 (SET-3) 
 
     
(b) On reaction with benzene sulphonyl chloride, the primary amine yields a 
product soluble in alkali, whereas the secondary amine yields a product 
insoluble in alkali. 
 
SECTION C 
 
13.  [3] 
(a) Following reaction takes place in the cell: 
      Zn
(s)
 + Ag
2
O
(s)
 + H
2
O
(l)
 ? Zn
2+
(aq)
 + 2Ag
(s)
 + 2OH
– (aq)
 
      Calculate ?
r
G° of the reaction. 
      [Given E°
(Zn2+/Zn)
  = -0.76V, E°
(Ag
+
/Ag)
 = 0.80 V, 1 F = 96,600 C mol
-1
] 
 
(b) How can you determine limiting molar conductivity 
? ?
m
? for a strong 
electrolyte and a weak electrolyte? 
 
14. Define the following with a suitable example of each:  [3] 
(a) Coagulation 
(b) Multimolecular colloid 
(c) Gel 
OR 
(a) Out of starch and ferric hydroxide sol, which one can easily be coagulated 
and why? 
(b) What is observed when an emulsion is centrifuged? 
(c) What is the role of promoters and poisons in catalysis? 
 
 
15.   [3] 
(a) An element crystallises in a bcc lattice with a cell edge of 3 × 10
-8
 cm. The 
density of the element is 6.89 g cm
-3
. Calculate the molar mass of the 
element (N
A
 = 6.022 × 10
23
 mol
-1
). 
(b) What type of semiconductor is obtained when 
(i) Ge is doped with In 
(ii) Si is doped with P 
 
16. A 0.1 M solution of Na
2
SO
4
 is dissolved to the extent of 95%. What would be 
its osmotic pressure at 27°C? (R = 0.0821 L atm K
-1
mol
-1
)  [3] 
 
17. Write down the reactions taking place in a blast furnace related to the 
metallurgy of iron in the temperature range 500–800 K. What is the role of 
limestone in the metallurgy of iron?  [3] 
 
OR 
What happens when 
(a) Silver is leached with NaCN in the presence of air? 
  
 
CBSE XII  | CHEMISTRY 
Board Paper – 2019 (SET-3) 
 
     
(b) Copper matte is charged into a silica-lined converter and a hot air blast is 
blown? 
(c) NaCN is added in an ore containing PbS and ZnS during concentration by 
the froth flotation method? 
 
 
18.  Give reasons for the following: [3] 
(a) Acidic character decreases from N
2
O
3
 to Bi
2
O
3
. 
(b) All the P–Cl bonds in PCl
5
 are not equivalent. 
(c) HF is a weaker acid than HCl in an aqueous solution. 
 
19. Write the structures of monomers used to obtain the following polymers : [3] 
(a) Natural rubber 
(b) PVC 
(c) Nylon-6.6 
 
OR 
Write the mechanism of free radical polymerisation of ethane. 
 
20.   [3] 
(a) Why are metal hydroxides a better alternative than sodium hydrogen 
carbonate in antacids? 
(b) Why is aspirin used in the prevention of heart attacks? 
(c) Why do antihistamines not affect the secretion of acid in the stomach? 
 
OR 
Define the following terms with a suitable example of each: 
(a) Tranquillisers 
(b) Antibiotics 
(c) Non-ionic detergents 
 
 
21.  [3] 
(a) Out of  and , which one is more reactive towards the 
S
N
2 reaction and why?  
(b) Out of  and , which one is more reactive towards the 
nucleophilic substitution reaction and why?  
(c) Out of  and , which one is optically active and why? 
 
 
22. What happens when  [3] 
  
 
CBSE XII  | CHEMISTRY 
Board Paper – 2019 (SET-3) 
 
     
(a) Sodium phenoxide is treated with CH
3
Cl 
(b) CH
2
=CH–CH
2
–OH is oxidised by PCC 
(c) Phenol is treated with CH
3
COCl/anhydrous AlCl
3
 
Write chemical equations in support of your answer. 
 
23.   [3] 
(a) Give one chemical test as evidence to show that [Co(NH
3
)
5
Cl]SO
4 
and 
[Co(NH
3
)
5
(SO
4
)]Cl are ionisation isomers. 
(b) [NiCl
4
]
2
?
 is paramagnetic, while [Ni(CO)
4
] is diamagnetic though both are 
tetrahedral. Why? (Atomic no. of Ni = 28) 
(c) Write the electronic configuration of Fe(III) on the basis of crystal field 
theory when it forms an octahedral complex in the presence of (i) strong 
field ligand and (ii) weak field ligand. (Atomic no of Fe = 26) 
 
 
 
24.  Define the following terms with a suitable example of each:  [3] 
(a) Tertiary structure of protein 
(b) Essential amino acids 
(c) Disaccharides 
SECTION D 
25.   [5] 
(a) Predict the main product of the following reactions:  
(i)  
 
 
(ii)  
  
 
(iii)  
  
 
(b) Give a simple chemical test to distinguish between 
 and  
(c) Why is alpha ( ?) hydrogen of carbonyl compounds acidic in nature? 
OR