Monday, June 19, 2017

AHSEC - Class 12 Question Paper: Chemistry' 2016

(New Course)
Full Marks: 70
Pass Marks: 21

Time: 3 hours
The figures in the margin indicate full marks for the questions

1. Name one substance other than hydrogen that can be used for constructing fuel cells. 1
2. The curve showing the variation of adsorption with pressure at constant temperature is called ____. (Fill in the blanks) 1
3. What are Ores? Name one sulphide ore. 1
4. Mention the basicity of. 1
5. Define enantiomers. 1

6. Write the structural formula of propane – 1, 2, 3-triol. 1
7. Arrange the following in increasing order of pKa values: 1
8. Name two carbohydrates which act as bio-fuels. 1/2 + 1/2 = 1
9. Define semiconductors. Name the kind of semiconductor formed when Si is doped with Ga. 1+1=2
10. Calculate atomic radius of elementary silver which crystallizes in face-centered cubic, lattice with unit cell edge length. 2
Aluminium crystallizes as face centered cubic lattice and it has a density of. Calculate edge length of the unit cell. Given atomic mass of aluminium equal to 27.0amu 2
11. Represent the cell with cell reaction –
Calculate the emf of the cell at 298 K if the molar concentrations of and icons in the half cells are and respectively. Given that and    1+1=2
12. A current of 0.5 ampere is passed for 30 minutes through a volt ammeter containing copper sulphate solution. Calculate the mass of Cu deposited at the cathode. Given that atomic mass of Cu is 63.0amu. 2
13. (a) The rate of a reaction is equal to rate constant of the reaction. Mention the order of the reaction. 1
(b) Give the definition of collision frequency. 1
14. (a) Explain the role of in the electrolytic reduction of alumina. 1
(b) How does the FeO impurity present in sulphide ore of copper is removed? 1
15. Name the catalyst used for conversation of to in the contact process. How is oleum formed from in this process? 2
16. (a) Transition metal compounds are generally coloured. Why? 1
(b) What are interstitial compounds? 1
17. Identify A, B, C and D in the following conversions:
18. How will you convert aniline into phenol? Give necessary chemical equations. 2
19. Answer either (a) or (b):
(a) (i) Given one example of pseudo 1st order reaction.
(ii) A reaction is second order with respect to a reactant. How the rate of the reaction be affected if concentration of the reactant is reduced to half? 2
(b) Show that time required for completion 3/4th of a first order reaction is twice the time required for completion of 1/2 of the reaction. 3
20. Explain the terms: (any three) 1+1+1=3
  1. Emulsification.
  2. Coagulation.
  3. Dialysis.
  4. Electrophoresis.
21. Answer the following: (any three)
  1. Aqueous solution of is colourless, but aqueous solution of is violet in colour. Explain.
  2. Copper (I) had configuration, while Copper (II) has configuration. Still Copper (II) is more stable in aqueous solution than Copper (I). Why?
  3. What are lanthanoids?
  4. Give the chemical equation for the reaction between a saturated solution of sodium dichromate and potassium chloride.
22. (a) Write the formula of lithium tetrahydridoaluminate (III). 1
(b) What are the ambidentate Ligands? Give one suitable example of ambidentate Ligands. 1+1=2
23. (a) In the following halogen compounds, which one will readily undergo reaction? 1
(b) What happens when bromo-cyclohexane is treated with Mg in presence of dry either and the product is hydrodysed? Give chemical equations. 2
24. Answer the following: (any three) 1+1+1=3
  1. Explain why alcohols are more soluble in water compared to ethers.
  2. What happens when phenol is heated with Zn dust? Give chemical equation.
  3. Name the following chemical reaction:

25. Answer either (a) or (b): 1+1+1=3
(a) (i) What is Zwitter ion?
(ii) Name a source of vitamin E.
(iii) Name the disease caused due to deficiency of vitamin K in our body.
(b) (i) What enzymes?
(ii) What kind of linkages holds together monomers of DNA?
(iii) What is Denaturation of protein?
26. (a) Name the monomers of Bakelite. 1
(b) What does PVC stand for? Mention its one use. 1/2 + 1/2 =1
(c) Give one example of addition polymer.
27. Answer either (a) or (b)
(a) (i) Name a substance which can act as non-narcotic analgesic. 1
(ii) What are antibiotics? Give an example of antibiotics. 1+1=2
(b) (i) Why do we require artificial sweetening agent? 1
(ii) What are antacids? Give one suitable example. 2
28. (a) Mention a method used for desalination of sea water. 1
(b) Define the term ‘osmotic pressure’. How osmotic pressures of a solution vary with temperature?     1+1=2
(c) Calculate molarity of a solution containing in solution. 2
29. Answer either (a) and (b) or (c) and (d)
  1. Complete the following reactions:
  1. Draw the structural formula of. How do you account for reducing behaviour of on the basis of its structure? 1+1=2
  1. When reacts with finely powdered iron, it forms ferrous chloride and not ferric chloride. Explain, why?   2
  2. What are interhalogen compounds? Give a method of preparation of any one interhalogen compound. 1+2=3
30. Answer either (a) and (b) or (c) and (d):
  1. Give a chemical test with equation to distinguish between methanal and enthanal. 2
  2. An organic compound has the molecular formula. The compound does not reduce Tollen’s reagent, but reacts with Brady’s reagent to give orange precipitate. On vigorous oxidation, the molecule produces ethanoic acid and propanoic acid. The compound also gives iodoform test. Identify the compound and write equations for chemical reactions involved. 3

  1. What happens when carbonyl compound is treated with zinc-amalgam and concentrated hydrochloric acid? Give chemical equation. What is the name of the reaction? 2
  2. Discuss the mechanism of aldol condensation. 3


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