Sub. code 3021
NEB — GRADE XII
2083
Old Question
Chemistry Question Paper 2083 (Old Question)
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 question paper is for Class 12 Chemistry, 2083 (subject code 3021), carrying full marks of 75 with a pass mark of 32, to be completed within 3hrs. Answers with step-by-step solutions are available for every question below.
Group A
Write the correct option of each question in your answer sheet.
Which order of reaction does the following chemical equation represent?
Zero order
Pseudo-first order
Second order
Third order
What is the normality of 5% Na₂CO₃ solution?
0.94 N
0.98 N
0.99 N
1.01 N
Which of the following is the ionic product of water at 393 K?
Greater than
Less than
Equal to
Equal to
For what purpose is the hydrogen-oxygen fuel cell used in spacecraft?
Power for heat and light
Power for pressure
Power for propulsion
Power for uplift
Which of the following indicates lithophone?
Which of the following is the purest form of iron?
Cast iron
Steel
Haematite
Wrought iron
Nitrobenzene can be prepared from benzene by using a mixture of conc. nitric acid and conc. H₂SO₄ in the nitrating mixture. What is the role of nitric acid?
A base
An acid
A catalyst
A reducing agent
You are given (I) aniline, (II) o-nitroaniline, (III) p-nitroaniline and (IV) m-nitroaniline. What is the order of increasing basic nature?
II < I < III < IV
I < II < III < IV
II < III < I < IV
II < III < IV < I
Which of the following mechanisms can occur in the hydrolysis of isopropyl chloride?
SN¹ Mechanism
SN² Mechanism
SN¹ and SN² Mechanism
Neither SN¹ nor SN² Mechanism
What would be the product when benzaldehyde is heated with conc. NaOH?
Benzyl alcohol and sodium benzoate
Sodium benzoate and benzaldehyde
Sodium benzoate and benzene
Benzyl alcohol and benzene
A compound 'X' undergoes reduction with LiAlH₄ to yield 'Y'. When 'Y' is passed over copper heated to 300°C, 'X' is formed. What is 'Y'?
Acetone
Ethanal
Ethanol
Ethoxyethane
Group B
short answer question
Write any two differences between primary standard and secondary standard substance.
3.15 g of oxalic acid crystal (C₂H₂O₄·2H₂O) was dissolved in water to make 500 mL of its solution.
Determine the normality of the acid.
The acid solution became permanently pink when 400 mL of KMnO₄ solution (Eqv. Wt. = 31.5) was added during titration. What mass of KMnO₄ is present in 1 liter of the solution?
Why is standard hydrogen electrode called reference electrode?
An electrochemical cell connects Zn²⁺/Zn electrode with standard hydrogen electrode and the emf of the cell is found to be +0.76 V.
Design cell notation indicating cathode and anode.
Write down net cell reaction.
What is the value of E°Zn²⁺/Zn?
State Hess’s law of constant heat summation and illustrate it with an example.
Heat of formation of CO₂ and H₂O are −94 kcal and −68 kcal, respectively. Calculate heat of reaction when 2 moles of CH₄ is formed.
Identify A and B in the following reaction sequence.
Write the correct chemical equations to identify A and B.
What product would you obtain when A is:
Boiled with water?
Treated with aniline?
What happens when C₆H₅Cl is heated with chloral?
A list of organic compounds is given as follows:
Propanamine, ethoxyethane, ethyl cyanide, iodoethane and ethanol.
Prepare a correct sequence of reaction chain from the above compounds using suitable reagents and conditions.
An organic compound A gives compound B when heated with silver powder. Compound B undergoes hydrolysis with water in the presence of dil. H₂SO₄ and 1% HgSO₄ to yield C. Compound C reacts with dilute alkali to form D. Compound C can also be obtained by reduction of ethanoyl chloride with hydrogen in the presence of Pd/BaSO₄. Identify A, B, C and D with pertinent reactions.
Give an example of each of the following reactions.
Tollen’s test
Cannizzaro’s reaction
Decarbonylation
Reimer-Tiemann’s reaction
Oxo-process
Starting from CH₃MgBr, how would you prepare ethanoic acid? Write the action of ethanoic acid on:
i. NH₃
ii. SOCl₂
iii. P₂O₅
iv. LiAlH₄
Write down the preparation, properties, and uses of mercuric chloride.
A metal having electronic configuration [Ar] 3d¹⁰4s¹ belongs to IIB of the periodic table. The metal is widely used to make electric wires and domestic cooking utensils.
Draw a well-labelled blast furnace for smelting the metal from its ore.
Write down chemical reactions that occur in the smelting process.
Group C
long answer question
Write any two differences between order and molecularity of a reaction.
Draw a graph showing the relationship between concentration of reactant and time for a zero-order reaction.
The experimental data for a hypothetical reaction is:
Expt. no. | [X] mol L⁻¹ | [Y] mol L⁻¹ | Initial rate, mol L⁻¹ s⁻¹ |
|---|---|---|---|
I | 0.5 | 0.5 | 1.6 × 10⁻⁴ |
II | 0.5 | 1.0 | 3.2 × 10⁻⁴ |
III | 1.0 | 1.0 | 3.2 × 10⁻⁴ |
Determine the rate constant and write down the rate law equation from the above data.
What is the order of reaction with respect to ?
What is meant by weak electrolyte?
Derive Ostwald’s dilution equation.
Point out any two limitations of Ostwald’s dilution law.
Predict whether precipitation will occur or not on mixing 20 mL of of NaCl solution with 80 mL of AgNO₃ solution if for AgCl = . [At. wt. of Ag = 108 amu.]
Explain Hoffmann’s method to separate ethanamine and N-methylmethanamine from their mixture.
what happens when:
Chloroform is treated with acetone in presence of aq. KOH?
Ethanal reacts with 2,4-DNP?
Aniline is added to ice-cold solution of sodium nitrite and hydrochloric acid?
Nitro-benzene is subjected to electrolytic reduction?
Identify A, B, C and D in the following reaction sequence.
Compound ‘C’ can be obtained by Clemmensen’s reduction of benzaldehyde.
Explain the test of propan-1-ol and propan-2-ol by using Victor Meyer’s method in detail.
Explain the quality control system in the manufacture of Portland cement.
Give the correct structure of the following compounds.
i. Aspirin
ii. DDT
Write any two differences between paper and pulp.
What is meant by artificial radioactivity? Write an example of it.