Chemistry  – Important Question Bank for Bihar Class 12th Intermediate (HSC) Board Exam 2017 

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Bihar Chemistry question paper

1. What is a Semiconductor ? Describe the two main types of Semiconductors and explain the mechanism for their conduction.
2. Aluminium crystal allies in a cubic close packed structure. Radius of the atom in the metal is 125 pm.

(i) What is the length of the side of the unit cell

(ii) How many unit cells are there in 1cm³ aluminum

3. If the radius of the octahedral void is r and the radius of the atoms in the close packing is R, derive relationship between r and R
4. How would you account for the following ?

(i) Frenkel defects are not found in alkali metal halides.

(ii) Schottky defects lower the density of related solids.

(iii) Impurity doped silicon is a semiconductor.

5. Vapor pressure of Chloroform (CHCL₃) and dichloromethane (CH₂CL₂) at 298k are 200mm Hg and 415mm Hg respectively.

(i) Calculate the vapor pressure of the solution prepared by mixing 25.5g of CHCL₃ and 40g of CH₂CL₂ at 298k.

 (ii) Calculate the mole fraction of each Component in vapor phase.

6. 19.5g of CH₃FCOOH is dissolved in 500g of water. The depression in the freezing point observed is 1.0˚C. Calculate the van’t Hoff factor and Dissociation constant of fluoroacetic acid. K_f for water is 1.86k kg mol^-1?
7. What is osmotic pressure? Determine the osmotic pressure of a solution prepared by dissolving 25mg of K₂SO₄ in 2 liters of water at 25˚C, assuming that it is completely dissociated
8. Explain the term ideal and non-ideal solute in liquid solution. Draw graphs for illustration.
9. Three electrolytic cells A, B and C containing electrolytes ZnSO₄, AgNO₃ and CuSO₄ respectively were connected in series. A steady current of 1.50 ampere were passed through them until 1.45g of Ag were deposited at the Cathode of cell B. How long did the current flow? What mass of copper and zinc were deposited?
10. The following Chemical reaction is occurring in an electrochemical cell

Mg (S) + 2 Ag ⁺ (0.0001M)                Mg² + (0.10M) + 2Ag (S)

 The E˚ electrode Valves are

Mg² / Mg = – 2.36 V and Ag⁺ / Ag = 0.81V

For this cell Calculate

(a) (i) E˚ value for the electrode 2 Ag⁺ / 2 Ag

      (ii) Standard cell potential E˚ cell

(b) Cell potential (E ^cell)

(c) (i) Symbolic representation of the above cell.

      (ii) Will the above cell reaction be spontaneous.

11. What is Gibbs free energy? What is the relationship between Gibbs free energy of the cell reaction in a galvanic cell and the emf of the cell. When will the maximum work be obtained from a galvanic cell.
12. What are the applications of adsorption in Chemical analysis?
13. Discuss the effect of pressure and temperature on the adsorption of gases on solid.
14. What are micelles? How do they differ from ordinary colloidal particles? Give two example of micell forming substance.
15. Taking two examples of heterogeneously catalyzed reaction, explain how a heterogeneous catalyst helps in the reaction.
16. State Raoult’s Law for a solution. How does Raoult’s law became a special case of Henry’s law ?
17. What is meant by the term “concentration of the ore”? Describe the various methods used for this purpose.
18. .Describe the principle of extraction of each of the following:

(i) Cu from CuFeS₂ (ii) Zn from ZnO (iii) Fe from Fe₂O₃

19. Explain the following :

(a) Carbon reduction process is not applied for reducing alumina to aluminum.

(b) Aqueous solution of Sodium chloride cannot be used for isolation of solution by electrolysis.

(c) Graphite is used as anode and not diamond.

(d) Magnesium oxide is often used as the lining in steel making furnaces.

20. Explain, with proper reason, why nitrogen is a gas while other members of group-15 are solids
21. Give complete reaction between 2-chloropropane & KOH_alc on warming.
22. What happens when – Sodium ethanoate is heated with soda-lime.
23. Give complete reaction between on warming 2-chlorobutane with alcoholic KOH.
24. Name the reactant to obtain Propan-2-ol from CH₃MgI.
25. Name the reactant to obtain 2-Methyl Propan-2-ol from CH₃MgBr
26. What happens when methanol & conc. H₂SO₄ (1:1) are heated at 373 K?
27. Give complete reaction when ethanol and conc. H₂SO₄ (1:2) are heated at (433 K-443 K).
28. Complete the reaction When C2H5OH & conc. H2SO4 (1:1) are first heated at 373 K & then hydrolyzed?
29. Give the reaction When vapor of – Butanol is passed over Cu at 573 K
30. Complete the reaction when vapour of –

      2-methyl-butan-2-ol is passed through red hot Cu-tube?

31. Give the reaction only to prepare Aspirin from Salicylic Acid.
32. Complete the reaction when ethanamine is treated with (NaNO₂ & dil HCl).
33. What happens when benzenediazonium salt is heated with H3O⁺?
34. What happens when Benzene daizonium chloride is reduced?
35. What happens when ethanamine is treated with ethanoic anhydride?
36. Give only two important points to differentiate sn¹ and sn² reaction
37. Explain Aromaticity
38. Explain why Cl-Gr is –I effecting in alkyl chloride whereas the same Cl-Gr is +I effecting in Chlorobenzene?
39. Outline the synthesis of Picric Acid startin from phenol
40. How Bakelite is synthesized?