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NEB-GRADE XII
Candidates are required to give their answers in their own words as far as practicable. The figures in the margin indicate full marks.
Time: 3 hrs.
Attempt all the questions.
Group 'A' [11x1=11]
Rewrite the correct options for each question in your answer sheet.
1. 2R-OH+2Na → 2RONa+H,, is an example of
A) acidic nature of alcohol (✓)
B) basic nature of alcohol
C) electrophilic substitution reaction
D) nucleophilic substitution reaction
2. CH₂CH₂-CHO and C H₂CHO can be distinguished by;
A) iodoform test
B) Tollen's test
C) 2,4-DNP test
D) Fehling test (✓)
3. An organic compound (X) undergoes reduction with LIAIH, to yield (Y).When the vapor of y is passed over freshly reduced copper at 300°C (X) is formed. Compound Y is,
A) CH,CHO
B) CH₂CH₂-OH (✓)
C) CH,-CO-CH,
D) CH,-O-CH,
4. The number of possible structural isomers of 1° amines of molecular formula CH,,N give
A) I
B) 2
C) 3
D) 4 (✓)
5. Acetic anhydride is obtained from acetyl chloride by the reaction of
A) Conc.H₂SO₂
B) P₂05
C) CH,COONa (✓)
D) CH₂COOH
6. A metal (M) forms thiosulphate with the molecular formula M₂S₂O₁. The valency of Metal is
A) 1 (✓)
B) 2
C)3
D) 4
7. The PH of 10-8 M aqueous solution of HCI is
A) less than 7 (✓)
B) 7
C) 8
D) more than 8
8. A catalyst accelerates the reaction because
A) it brings reactants closer
B) it lowers the activation energy (✓)
C) it increases the activation energy
D) it forms a complex with the reaction
9. What is the concentration of nitrate ions if an equal volume of IM NANO and IM KCl are mixed
A) 0.25M
B) 0.5M (✓)
C) 1M
D) 2M
10. Bell metal is an alloy of
A) HgO
B) Hg₂0 (✓)
C) HgO₂
D) Hg₂O₂
11. Tailing of mercury is due to the formation of
A) Cu, Pb, and Sn
B) Sn and Cu (✓)
C) Zn and Pb
D) Zn, Cu, and Sn
Group 'B'
12. An electrochemical cell is constructed by using aluminum and silver electrodes whose electrodes potential values are;
Eº Ag/Al=-1.67V
Eº Ag/Ag= 0.80V
i) What is meant by an electrochemical cell?
ii) Represent an electrochemical cell using the above electrodes
iii) Write down complete cell reactions
iv) Calculate the emf of the cell
(1+1+2+1)
Or
Hess's law is applied to calculate the different types of enthalpy of reactions
i) Define Hess's law of constant heat summation.
ii) What is meant by the enthalpy of reaction?
iii) Standard enthalpy of formation of H₂O₂ (1) and H₂O (1) is- 188 KJ/mol and 286 kJ/mol respectively. What will be the enthalpy change of the following reaction:
2H₂O₂(1)→ 2H₂O(l) +0₂(g)
(1+1+3)
3. Ionic product of water at 25° C is 1×10-¹4 and water is regarded as a very weak electrolyte.
i) Define the ionic product of water.
ii) Deduce the relation Kw = [H] [OH]
iii) Calculate the [OH"] concentration of 0.01 M HCl at 25°C
iv) What is the effect of temperature on an ionic product of water?
(1+1+2+1)
14. Ethyl alcohol is common alcohol and is used to manufacture alcoholic beverages. It can be prepared from sugar-containing materials like molasses by fermentation process.
i) Define fermentation
ii) What is meant by molasses?
iii) Mention the function of yeast in the fermentation of ethyl alcohol.
iv) Write the chemical reaction for the conversion of cane sugar into ethyl alcohol.
v) Give a difference between absolute alcohol and denaturated alcohol.
(1+1+1+1+1)
15. A carbonyl compound (M) contains three carbon atoms and it undergoes iodoform test.
i) identify the compound (M)
ii) write down a chemical reaction for the preparation of (M)
iii) How is (M) converted into propane ?
iv) Predict the final product obtained when (M) is treated with CH,Mgl in presence of dry ether and followed by hydrolysis ?
v) Give a laboratory test reaction of carbonyl compound.
(5x1)
Or
Convert ethoxy ethane from a halo alkane C₂H,Br by using Williamson's reaction.
i) What product is obtained when ethoxyethane is heated with excess HI ?
ii) Why are old sample of ether not distilled to dryness air ?
iii) Convert phenol into anisole.
(1+2+2)
16. For the following reaction sequence.
i) Write down reagents and conditions for reaction (1), reaction (2), reaction (3) and reaction (4).
ii) Identify the compound (2) giving IUPAC name.
(4+1)
17. How would you apply Hoffmann's method for the separation of 1º, 2º and 3º amine from their mixture ?
18. An important compound non typical transition metal zinc which is used as eye lotion and is also called white vitriol.
i) Write down a method of preparation of white vitriol.
ii) What happens when white vitriol is heated to 800°C ?
iii) Define double salt giving an example of it
iv) How is Lithopone obtained from white vitriol.
v) Why is zinc considered as non typical transition metal.
(5x1)
19. Steel manufactured by Open Hearth process.
i) What is open Hearth process ?
ii) Write down the chemical reactions occurring in Open-Hearth furnace.
iii) Why is Speigeleisen added in the Open-Hearth furnace ?
iv) Write down the composition of stainless steel.
(1+2+1+1)
Group 'C'
20. a) Write an example of each of the following reactions.
i) Hydroboration oxidation
ii) Decarbonylation
iii) Sandmeyer's reaction
iv) Todoform reaction
v) Elimination reaction
vi) Cannizzaro's reaction
vii) Reimer-Tiemann reaction
viii) Fridel Craft alkylation
(8x1=8)
Or
An unsaturated hydrocarbon (C₂H) undergoes Markovikov's rule to give (A). Compound (A) is hydrolysed with aqueous alkali to yield (B). When (B) is treated with PBr,, compound (C) is produced. (C) reacts with AgCN (alc.) to give another compound (D). The compound (D) if reduced with LIAIH, produce (E).
i) Define Markovikov's rule.
ii) Identify (A), (B), (C), (D) and (E) with chemical reaction.
iii) How does E react with nitrous acid ?
iv) How would you convert (B) into C3H8?
(1+5+1+1)
21. a) For a hypothetical chemical reaction mP+nQ→z; the rate Law is, rate K [P] [Q]". Where K is rate constant of the reaction (m + n) are overall order.
i) Define rate law.
ii) Why is rate law experimental parameter ?
iii) What is meant by rate constant ?
iv) Mention a difference between order and molecularity of a reaction.
(4x1)
b) For the above reaction, the order of reaction with respect to P and Q are first order and zero order respectively. Experimental data obtained from the reactions are; as below.
i) Identify the value of A, B and C
ii) Calculate rate constant [k].
Or
a) Crystal of oxalic acid is generally used to prepare primary standard solution.
i) Define primary standard solution.
ii) Which chemical indicator is used in the titration of KMnO, solution verses oxalic acid solution ?
iii) Why is oxalic acid solution warmed adding dilute H₂SO, before titrating With KMnO, ?
iv) Mention a major application of titration in quality control laboratory.
(1+1+1+1)
b) An aqueous solution of a dibasic acid containing 17.7 gm of acid per- litre of the solution, has density 1.0077gm/litre (molar mass of the acid=118gm/mol) Calculate;
i) molarity
ii) molality
(2+2)
22 a)
i) What is Portland cement ?
ii) Name the major components present in Portland cement.
iii) Why is gypsom used in clinker during cement production process?
iv) Give any two instruments used for the quality control of cement.
(1+1+1+1)
b)
i) Differentiate between homo-polymer and co-polymer giving an example of each.
ii) Name the monomers of the following polymer and also write their molecular formula.
a) Polystyrene
b) Bakelite
(2+2)
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