Sub. code 3021
NEB — GRADE XII
Set B
Model Question
Class 12 Chemistry Model Question Set B
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 B (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 option in your answer sheet
Which indicator is used for this titration shown in figure?
methyl orange
phenolphthalein
litmus paper
both methyl orange and phenolphthalein
What is the pH of the solution of 10 mL H₂SO₄ of 10⁻⁷ M?
0
< 7
7
> 7
Half life period is directly proportional to the initial concentration of the reactant. What is the order of the reaction?
zero order
second order
first order
third order
In which of the following vessel aqueous CuSO₄ solution can be safely stored?
Zn-vessel
Fe-vessel
Al-vessel
Ag-vessel
Which of the following metal forms amphoteric oxide?
Fe
Ni
Cu
Zn
A white solid halide of metal forms a white precipitate mixture with ammonia. Which of the following is the halide?
HgCl₂
HgI₂
Hg₂I₂
Hg₂Cl₂
Which of the following has most acidic proton?
CH₃COCH₃
(CH₃)₂C=CH₂
CH₃COCH₂CH₃
(CH₃CH₂)₃CH
What is the product formed when Grignard reagent reacts with CH₃CN followed by hydrolysis?
alcohol
aldehyde
ketone
carboxylic acid
What does the compound (B) gives under Clemmensen’s reduction?
benzaldehyde
benzoic acid
toluene
benzene-nitrile
How many isomeric alcohols are formed from propanol?
2
3
4
5
How can we convert an alkyl halide into alkene?
substitution
addition
elimination
reduction
Group B
Short answer question
Define the term primary standard substance
Why is titration between weak acid and weak base not common?
If 10 mL of N/10 (f = 1.01) oxalic acid neutralized 10 mL of x% (w/v) NaOH solution. Find the value of x.
Gibb’s free energy was introduced to explain spontaneity of thermodynamic process. Mathematically, ΔG = ΔH – TΔS
Define Gibb’s free energy change.
Predict the spontaneity if ΔH and ΔS are positive.
ΔH and ΔS for chemical reaction is found to be 50 kJ mol⁻¹ and 300 J mol⁻¹ K⁻¹. Is the reaction spontaneous at 15°C?
Draw well labelled diagram of standard hydrogen electrode.
Why is it called reference electrode?
You are given E°Zn²⁺/Zn = –0.76 V, E°Pb²⁺/Pb = –0.13 V design a cell notation for an cell and calculate emf of the cell.
A transition metal ‘M’ forms bluish white precipitate with NaOH solution having atomic mass 63.5.
Identify the metal ‘M’ and give chief ore of it.
Write down different chemical reaction occurring in blast furnace during smelting process of the metal.
Name the method used for the refining of the metals.
Write the chemistry of corrosive sublimate.
Write the principle behind the preparation of trichloromethane from acetone.
What happens when chlorobenzene is heated with:
List of organic compounds are as follows:
A: C₂H₆O = CH₃CH₂OH (Ethanol)
B: C₂H₅Cl = CH₃CH₂Cl (Chloroethane)
C: C₂H₄O₂ = CH₃COOH (Ethanoic acid)
D: C₂H₄O = CH₃CHO (Ethanal)
E: C₄H₁₀O = CH₃CH₂–O–CH₂CH₃ (Diethyl ether)
How can you convert A to B if compound A responds positive iodoform test?
How is D obtained from A?
Make a sequence of reaction to convert A into C.
What happens when E is treated with O₂ in presence of sunlight?
Give an example of following chemical reactions.
a) Diazotization
b) Perkin Condensation
c) Reimer–Tiemann reaction
d) Esterification
e) Dow’s process
A list of compounds are given as follows:
benzamide, aniline, benzene, benzoic acid, toluene
Prepare a correct sequence of reaction with suitable condition and reagents.
Group C
Long answer question
A hypothetical reaction, 3X + 2Y ⟶ Z
Expt | [X] (mol L⁻¹) | [Y] (mol L⁻¹) | The Rate of formation of Z (mol L⁻¹ min⁻¹) |
|---|---|---|---|
1 | 0.1 | 0.1 | 1 × 10⁻³ |
2 | 0.1 | 0.4 | 4 × 10⁻³ |
3 | 0.2 | 0.4 | 8 × 10⁻³ |
4 | 0.5 | A | 1.8 × 10⁻² |
a) Determine the value of rate constant.
b) Calculate the value of A.
c) Write rate law equation.
What is pseudo first order reaction? Write one suitable example.
Draw the diagram showing effective collision.
Differentiate between ionic product and solubility product.
Point out the limitation of Ostwald’s dilution law.
Why is aqueous solution of sodium chloride neutral?
Given that Ksp for BaSO₄ is 1 × 10⁻¹⁰, will the precipitate form when:
i) Equal volumes of 2 × 10⁻³ M BaCl₂ solution and 2 × 10⁻⁴ M Na₂SO₄ solution are mixed.
ii) Equal volumes of 2 × 10⁻⁸ M BaCl₂ solution and 2 × 10⁻³ M Na₂SO₄ solution are mixed.
Explain Hofmann’s method for the separation of 1° and 2° amines from their mixture. What is meant by Hofmann’s ammonolysis?
What happens when ethanal reacts with:
a) 2,4-DNPH (2,4-dinitrophenyl hydrazine)
b) HCN
c) Tollens’ reagent
Cement is important material for construction of building, roads, bridges; etc.
a) Describe briefly different steps involved in Portland cement production with a flow-sheet diagram.
Differentiate between natural radioactivity and artificial radioactivity.
Write the raw materials for paper production.
Write any two differences between antipyretic and analgesic drugs.
Paper Overview & Analysis
Set B
Year
Model Question
Type
75
Full Marks
33
Pass Marks
3 Hours
Duration
44
Question Items
Question Type Breakdown
Group Breakdown
Chapter Breakdown
| Study of Heavy Metals | 5 items | 10 marks |
| Aldehydes and Ketones | 4 items | 6 marks |
| Amines | 3 items | 15 marks |
| Transition Metals | 2 items | 3 marks |
| Volumetric Analysis | 1 item | 1 mark |
| Ionic Equilibrium | 1 item | 1 mark |
| Chemical Kinetics | 1 item | 1 mark |
| Alcohols | 1 item | 1 mark |
| Haloalkanes | 1 item | 1 mark |
| Cement | 1 item | 2 marks |
| Nuclear chemistry and application of radioactivity | 1 item | 2 marks |
| Paper and Pulp | 1 item | 2 marks |
| Chemistry in the Service of Mankind | 1 item | 2 marks |
Chapter breakdown covers 23 of 44 question items on this paper — the rest aren't tagged to a chapter yet.
1 question item offered alternative ("OR") chapters and isn't attributed to either, since only one could be attempted.