Sub. code 3021
NEB — GRADE XII
2082
Old Question
Class 12 Chemistry Old Question 2082
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 : 32
सबै प्रश्नको उत्तर दिनुहोस् । (Attempt All Questions)
This old question paper is for Class 12 Chemistry, 2082 (subject code 3021), carrying full marks of 75 with a pass mark of 32, 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 of each question in your answer sheet
Half-life period of any first order reaction is:
equal to half of the rate constant
directly proportional to the initial concentration of the reactants
independent of initial concentration of the reactants
same for all reactions
What is the value of ionic product of water at 393 K?
Less than 1 × 10⁻¹⁴
Equal to 1 × 10⁻¹⁴
Greater than 1 × 10⁻¹⁴
Equal to 1 × 10⁻⁷
For equilibrium of H₂O(l) ⇌ H₂O(g), at 1 atm and 298 K, which condition is true?
ΔG < 0
ΔG > 0
0.5 M H₂SO₄ is diluted from 1 litre to 10 litre. What is the normality of resulting solution?
1 N
0.1 N
0.01 N
0.05 N
Which one of the following processes is applied for the galvanization of iron sheet?
Cu-plating
Sn-plating
Ag-plating
Zn-plating
What result do you find when molten zinc metal is poured into cold water?
Zinc dust
Granulated zinc
Hard zinc metal
Soft zinc metal
In the given reaction sequence, compound (C) is 2,3-dimethylbutane.
What compound is A?
Propyne
Butene
Butyne
Propene
How many isomeric unsymmetrical ethers are possible for C₄H₁₀O?
1
2
3
4
Wide-spread death is reported every year due to liquor poisoning. What compound causes such poisoning?
Methyl alcohol
Ethyl alcohol
Carbonic acid
Absolute alcohol
Which is the weakest acid among the following?
ClCH₂COOH
CCl₃COOH
ClCH₂COOH
CH₃COOH
An organic compound (A) on reduction gives compound (B). (B) on treatment with CHCl₃ and alcoholic KOH gives (C). (C) on catalytic reduction gives N-methylaniline. What compound is (A)?
Methylamine
Aniline
Nitrobenzene
Nitromethane
Group B
short answer question
Experimental data obtained by titrating deci-normal solution of Na₂CO₃ with unknown strength of H₂SO₄ solution are given below.
Expt. | Volume of Na₂CO₃ (mL) | Initial H₂SO₄ (mL) | Final H₂SO₄ (mL) |
|---|---|---|---|
I | 25 | 0.0 | 20.5 |
II | 25 | 0.0 | 20.0 |
III | 25 | 0.0 | 20.0 |
Name the above titration.
Which indicator is used in the above titration and why?
Calculate the normality of H₂SO₄ from the above data.
An electrochemical cell designed by dipping copper rod in 1 M CuSO₄ and silver rod in 1 M AgNO₃ solution is connected with salt bridge filled with KNO₃ solution. The standard electrode potential of Cu and Ag are +0.34 V and +0.80 V, respectively.
Draw an electrochemical cell indicating anode and cathode.
What is the function of salt bridge in the cell?
Write down the cell reaction and emf of the cell.
State Hess's law of constant heat summation. Enthalpy of formation of water H₂O(l), carbon dioxide CO₂(g) and benzene C₆H₆(l) are −286 kJ, −395 kJ and +52 kJ, respectively.
Give correct chemical equation for the standard enthalpy of combustion of benzene.
Calculate standard enthalpy of combustion of benzene.
Consider a reaction sequence:
In the above reaction sequence, compound (D) is a sleep-inducing drug.
Identify (A), (B), (C) and (D) in the above reaction sequence and also give their IUPAC names.
What product would you obtain when (A) is treated with dil. alkali?
Describe the Victor-Meyer’s test for the distinction of 1°, 2° and 3° alcohol.
Starting from benzene, how will you prepare aniline? What happens when aniline is treated with:
a. benzene diazonium chloride
b. aqueous bromine
c. benzaldehyde
Give an example of each of the following reactions:
a. 2,4-DNP test
b. Carboxylation
c. Dehydrohalogenation
d. Williamson's ether synthesis
e. Fehling's test
An aromatic halogen compound (A) undergoes reduction with Ni-Al in presence of alkali to give (B). The compound (B) is treated with CH₃Cl in presence of AlCl₃ to produce (C). Oxidation of (C) with acidified CeO₂ yields (D). The compound (A) can be prepared from Sandmeyer’s reaction.
Identify (A), (B), (C) and (D) with reactions and conditions involved.
How does (D) react with alc. KCN?
Write down any two balanced chemical equations for the preparation of calomel.
How does calomel react with:
i. Ammonia solution
ii. Stannous chloride (SnCl₂)
iii. Aqua regia
A flesh-pink metal (M) of valence shell electronic configuration 4s¹3d¹⁰ belongs to group (IB) in the periodic table. This metal is commonly used to make electrical appliances.
What is the chief ore of (M)? Write its molecular formula.
Draw a well-labelled diagram for the smelting of (M)
Write down necessary chemical equations that occur during smelting.
Group C
long answer question
What is meant by rate of reaction?
For a reaction X + Y → Z, the rate of reaction doubled when the concentration of X was doubled. However, the rate of reaction increased eight times when the concentration of both X and Y were doubled.
Determine order of the reaction.
Write down the rate law equation.
The following data were obtained for the reaction:
2NO₂(g) + F₂(g) → 2NO₂F(g)
Expt. No. | [NO₂] (mol L⁻¹) | [F₂] (mol L⁻¹) | Initial rate (mol L⁻¹ s⁻¹) |
|---|---|---|---|
1 | 0.20 | 0.05 | 6 × 10⁻³ |
2 | 0.40 | 0.05 | 1.2 × 10⁻² |
3 | 0.80 | 0.10 | 4.8 × 10⁻² |
Find out the rate of the above reaction when the concentration of [NO₂] and [F₂] are 0.50 and 0.60 mol L⁻¹, respectively.
Define solubility product principle. How are solubility product principle and common ion effect applied for the analysis of group II metal-ions in qualitative salt analysis?
Differentiate between Bronsted-Lowry acid and Lewis acid
Two solutions (A) and (B) have pH 3 and 5, respectively. What will be the pH of resulting solution prepared by mixing equal volume of (A) and (B)?
How is ethanoic acid prepared from:
i. ethanamide?
ii. sodium methoxide?
Convert ethanoic acid into:
i. methane
ii. methyl ethanoate
Write down two isomeric amines and their IUPAC name for C₂H₇N. How would you apply Hoffmann's method to separate them from their mixture?
You are given the following organic compounds:
A = C₄H₆O₃
B = C₂H₄O₂
C = C₂H₃OCl
D = C₂H₄O
E = C₄H₈O₂
where, compound (B) is monocarboxylic acid and compound (E) is commonly known as aldol. Complete the following reaction sequence identifying A, B, C, D and E with chemical equations and reagents.
A → B → C → D → E
Convert compound D into propanone.
Mention one use of:
i. Tranquilizer
ii. Antiseptics
What is Portland cement? Why is gypsum added to Portland cement?
Give the importance of wood pulp in paper industry.
Define nuclear fusion. Why is it called thermonuclear reaction?
Paper Overview & Analysis
2082
Year
Old Question
Type
75
Full Marks
32
Pass Marks
3 Hours
Duration
47
Question Items
Question Type Breakdown
Group Breakdown