Sub. code 3021
NEB — GRADE XII
Set A
Model Question
Class 12 Chemistry Model Question Set A
The candidates are required to give their answers in their own words as far as practicable. The figures in the margin indicate full marks.
Pass Marks : 33
सबै प्रश्नको उत्तर दिनुहोस् । (Attempt All Questions)
This model question paper is for Class 12 Chemistry, Set A (subject code 3021), carrying full marks of 75 with a pass mark of 33, to be completed within 3 Hours. Model answers are available for questions that have one — reveal them with a free account (a few reveals) or a paid plan (unlimited).
Group A
Rewrite the correct answer in your answer sheet
Two students are performing a titration of H₂SO₄ and Na₂CO₃. Which one of the following indicator would you advise select for the titration?
methyl orange
both phenolphthalein and methyl orange
litmus paper
phenolphthalein
Which of the following is the relation between solubility and product of sparingly soluble salt A₂B?
s = (Ksp)¹ᐟ²
s = [(Ksp)/2]¹ᐟ³
s = [(Ksp)/4]¹ᐟ³
s = [(Ksp)/(12B)]¹ᐟ⁵
Which reaction does the following represent?
zero order
first order
second order
third order
What is the bond energy of C–H bond of CH₄ for the given reaction?
C + 4H → CH₄, ΔH = –400 kcal
100 kcal
–100 kcal
200 kcal
–400 kcal
What is the number of d-electrons of Cr in [Cr(H₂O)₆]³⁺ ion?
2
3
4
5
With which chemical does the mercury sticks to the surface of glass?
H₂O
CO₂
H₂
O₃
Which of the following rule indicates that the more substituted product is favoured during elimination?
Markovnikov’s rule
Saytzeff’s rule
Victor-Meyer’s rule
Hofmann’s rule
Which of the following is the correct order of boiling point of following compounds?
A. CH₃CHO
B. C₂H₅OH
C. CH₃COOH
A > B > C
C > A > B
C > B > A
B > C > A
Which of the following reagent converts carboxylic acid to anhydride?
P₂O₅
CaO
LiAlH₄
Na/C₂H₅OH
What does the conc. HNO₃ act during the nitration of benzene?
acid
base
electrophile
nucleophile
Identify Z in the following reaction.
aniline
benzene diazonium chloride
phenyl isocyanide
nitrobenzene
Group B
Short answer questions
100 cc of N/2 HCl, 20 cc of N/10 HNO₃ and 50 cc of N/5 H₂SO₄ are mixed.
Find the resulting normality of mixture.
Calculate the pH of the mixture.
What is meant by decinormal solution?
For a gaseous reaction:
2A + B ⟶ C. The reaction is first order with respect to A and zero order with respect to B.
Define order of reaction.
Write the rate law for above reaction.
How many times the rate of reaction increase if the concentration of both A and B are doubled?
If the temperature increases by 20°C what will be its effect in rate of reaction?
Define heat of formation. Calculate the heat of formation of ethyl alcohol from given data.
Compound/Element — Heat of Combustion
Carbon → –94 Kcal
Hydrogen → –68.5 Kcal
Ethyl alcohol → –330 Kcal
Give the chemical reaction for the preparation of phenol from chlorobenzene.
Why is phenol more easily nitrated than benzene?
Convert phenol into phenolphthalein.
Write an example of each of the following chemical reactions.
a) Gattermann reaction
b) Reimer–Tiemann reaction
c) Cannizzaro’s reaction
d) Esterification reaction
e) Rosenmund reduction reaction
The list of organic compounds is given as follows:
propanoic acid, ethanol, ethanamine, chloroethane, propanamide
Prepare the correct sequence giving suitable conditions/reagents.
How is ethanoic acid prepared from the following compounds?
i. CH₃MgBr ii. CH₃CN iii. CH₃ONa
Convert ethanoic acid into methanoic acid.
A compound Y on treatment with dil. NaOH gives 3-hydroxybutanal
Identify the compound Y
Compound Y can be formed from an alkene. Name the alkene and write reactions involved.
How does Y react with HCN?
What are the assumptions of crystal field theory? Draw the diagram to show the splitting of d-orbitals in octahedral complex.
The transition metal having atomic number 80 is commonly known as quick silver.
Why is this metal known as quick silver?
Give the formula of chief ore of the metal.
Draw and write the chemical reaction that takes place in shaft furnace.
Group C
Long answer question
The standard reduction potential of three metals A, B and C are –0.76 V, +0.34 V and +0.80 V respectively.
Define standard reduction potential.
Give the order of reducing power of metal A, B and C.
Write the cell notation when B is connected with standard hydrogen electrode (SHE)
Write the complete cell reaction of above electrochemical cell.
Calculate the standard emf of the cell
Define degree of ionization.
State Ostwald’s dilution law
Derive the relation: α = √(K / C)
Calculate the degree of ionization of 0.01 M acetic acid having Kₐ = 1.8 × 10⁻⁵.
In the following reaction sequence:
Identify P, Q, R, S and T with necessary chemical reactions.
What happens when Q is heated with sodalime?
Convert compound S into p-hydroxyazobenzene.
Compound A having molecular formula C₃H₆O under reduction gives B. Both compound A and B respond to iodoform test.
Identify compound A and B giving chemical reactions.
Give any two general methods of preparation of compound A.
Convert the compound B into pseudonitrol.
How is the functional isomer of B prepared by William’s synthesis?
Define radioactivity and write its unit.
Give one example each for natural and synthetic polymer.
Write the raw materials for paper production.
Draw the flow sheet diagram for the manufacture of Portland cement.
Paper Overview & Analysis
Set A
Year
Model Question
Type
75
Full Marks
33
Pass Marks
3 Hours
Duration
53
Question Items
Question Type Breakdown
Group Breakdown
Chapter Breakdown
| Volumetric Analysis | 3 items | 4 marks |
| Haloarenes | 3 items | 8 marks |
| Ionic Equilibrium | 2 items | 3 marks |
| Thermodynamics | 2 items | 6 marks |
| Transition Metals | 2 items | 6 marks |
| Carboxylic Acid and its Derivatives | 2 items | 6 marks |
| Phenols | 2 items | 3 marks |
| Chemical Kinetics | 1 item | 1 mark |
| Study of Heavy Metals | 1 item | 1 mark |
| Haloalkanes | 1 item | 1 mark |
| Aldehydes and Ketones | 1 item | 1 mark |
| Amines | 1 item | 1 mark |
| Nitro Compounds | 1 item | 2 marks |
| Ethers | 1 item | 2 marks |
| Nuclear chemistry and application of radioactivity | 1 item | 2 marks |
| Chemistry in the Service of Mankind | 1 item | 2 marks |
| Paper and Pulp | 1 item | 2 marks |
| Cement | 1 item | 2 marks |
Chapter breakdown covers 27 of 53 question items on this paper — the rest aren't tagged to a chapter yet.