Sub. code 3021
NEB — GRADE XII
2081
Old Question
Chemistry Question Paper 2081 (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, 2081 (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
Rewrite the correct option of each question in your answer sheet
A chemical reaction occurs as follows:
What is the equivalent weight of ?
25
49
59
98
If solution of acetic acid is ionised, what will be the dissociation constant of acetic acid?
If the rate of reaction is equal to the rate constant, what will be the order of reaction?
Zero
First
Second
Third
Standard electrode potentials of four metals P, Q, R and S are , , and , respectively. Which is the correct arrangement in the order of decreasing reactivity?
S > P > Q > R
Q > R > P > S
R > Q > P > S
R > S > Q > P
What feature of transition metals makes them suitable to act as catalyst?
Large ionic charge
Variable oxidation state
Highly reactive nature
Large surface area for the reactant to be absorbed
Which of the following metal ions shows green color in its salt?
Benzene ‘X’ ‘Y’
If the compound ‘Y’ is heated with acid anhydride in the presence of sodium acetate, what will it give?
Cinnamic acid
Picric acid
Benzoic acid
Phthalic acid
Which of the following compounds gives positive Tollen's test as well as Iodoform test?
Propanone
Ethanol
Ethanal
Methanal
Which one of the following is most basic in nature?
Which of the following compounds reacts with chlorobenzene to form DDT?
Carbonyl chloride
Acetone
Chloral
Chloroform
If you are asked to prepare a primary alcohol using Grignard's reagent, what will you start with?
Methanal
Ethanal
Propanone
Acetyl chloride
Group B
short answer question
Standard reduction potentials of and are and , respectively.
Write down the cell notation indicating anode and cathode.
Calculate the standard emf of the cell.
Write the complete cell reaction.
Define heat of combustion.
Heat of combustion of carbon , sulphur and carbon disulphide are , and , respectively. Calculate the heat of formation of .
Define the term pH of a solution. Calculate the hydroxyl ion concentration in mole/litre of a solution whose pH is 4.7. Also determine the weight of NaOH required to produce these ions in one litre of the solution.
A coinage metal (M) of electronic configuration belongs to group IB in the periodic table.
Draw a blast furnace for the smelting process during the extraction of (M) using its chief ore.
Explain the different chemical reactions involved during the formation of matte in the furnace.
Give a reaction for the preparation of corrosive sublimate.
What is the action of corrosive sublimate with:
i) KI solution
ii) solution
iii) solution
Mention any two important uses of corrosive sublimate.
Starting from benzene, how would you prepare nitrobenzene? How would you convert nitrobenzene into:
i) Azoxybenzene
ii) p-Aminophenol
iii)Aniline
iv)Azobenzene
Identify compounds (A) and (B).
Starting from compound (A), how would you obtain 2,3-dimethylbutane?
Convert compound (B) into propene.
Predict the product when compound (A) is heated with sodium methoxide.
Make a correct sequence of reactions using suitable conditions from the following compounds
Benzoin, Toluene, Benzene diazonium chloride, Phenol, Benzaldehyde and Benzene
Write down a chemical equation of each of the following.
i) Carbonylation reaction
ii) Fehling's test
iii) Aldol condensation
iv) Williamson's ether synthesis
v) 2,4-DNP test
Write an example of each of primary (1°) and secondary (2°) alcohol. How is Victor-Meyer's test applied to distinguish between them?
Group C
long answer question
The concentration of solution can be determined by titration with standard solution.
Is the solution primary standard? Why?
Differentiate between equivalence point and end point.
Define half-life of a reaction. Deduce the relation that the half-life for a reaction is directly proportional to the initial concentration of reactant.
For a reaction:
Expt. No. | Initial M | Initial M | Initial rate of disappearance of (M/min.) |
|---|---|---|---|
1 | 0.15 | 0.15 | 0.60 |
2 | 0.15 | 0.30 | 1.20 |
3 | 0.30 | 0.15 | 2.40 |
4 | 0.25 | 0.25 |
Write the expression for rate law.
Calculate the value of and specify its unit.
Find the value of .
The vapour of organic compound (A), if inhaled, causes the loss of consciousness and if heated with conc. , forms a component of tear gas.
How would you prepare compound (A) by using one of the isomers of ?
What happens when compound (A) is:
(a) exposed in air
(b) heated with Ag powder
(c) condensed with acetone, and
(d) heated with aniline in the presence of alc. KOH?
Give reasons:
Ether is stored in the bottle containing iron wire.
Though ethanol is an organic compound, it is soluble in water.
A sequence of reaction in general form is expressed as:
Compound A is a carboxylic acid that produces ethanoic anhydride on being heated with .
Identify A, B, C, D and E with reactions involved.
If compound A undergoes Hell–Volhard–Zelinsky reaction, write the reaction leading to the final product.
What product will be formed if compound B is treated with ethanol?
How would you convert compound ‘E’ into methanal?
What is Portland cement? List out the major constituents of Portland cement.
Give the structural formula of monomer and a use of each of the following:
i) Nylon 6,6
ii) Polystyrene
Differentiate between:
Nuclear reactions and chemical reactions.
Fibrous and non-fibrous raw materials for paper production.