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#### Important 3 Mark Creative Questions (New Syllabus) 2020

12th Standard EM

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Chemistry

Time : 01:00:00 Hrs
Total Marks : 90

Part A

30 x 3 = 90
1. What is meant by ammonia leaching?

2. What is the role of depressants in froth flotation process?

3. What are the applications of the Ellingham diagram?

4. Describe the structure of fullerenes.

5. Name a reaction for the estimation of Ozone.

6. Predict the product
(i) PCI5+ C2H5OH $\longrightarrow$?
(ii) P4+ S02Cl2 $\longrightarrow$ ?
(iii) POCl3 + H2O $\longrightarrow$ ?
(iv) HBr + PH3$\longrightarrow$ ? :,
(v) PCl3+ H20$\longrightarrow$ ?

7. Write chemical equations for the reactions involved in the manufacture of potassium permanganate from pyrolusite ore.

8. (i) Name the transition metal
(a) Which is used in the manufacture of sulphuric add.
(b) That is used in Haber's process.
(c) That have light sensitive properties and act as valuable source in photo graphic industry.
(ii) Write the equations which are involved in the oxidation of hydrogen sulphide to sulphur by KMnO4 solution.

9. Explain the oxidising property of KMnO4 in natural medium. Give the equations.

10. What is meant by unidentate, didentate and ambidentate Iigandst Give two examples for each.

11. What are the limitations of VBT?

12. Mohr's salt answers the presence of Fe2+, NH4+and SO42- ions, whereas the potassium ferrithiocyanate will not answer Fe3+ and SCN ions give reason.

13. Classify the following solids in different categories based on the nature of intermolecular force operating in them: Potassium sulphate, tin, benzene, urea, ammonia, water, zinc sulphide, graphite, rubidium, argon, silicon carbide.

14. (i) What change occurs when AgCl is doped with CdCI2?
(ii) What type of semiconductor is produced when silicon is doped with boron?

15. Prove that the time required for the completion ${ \frac { 3 }{ 4 } }^{ th }$ of the reaction of a first
order is twice the time required for the completion of a half of the reaction.

16. The decomposition of NH3 on platinum surface is zero order reaction what are the rates of production of N2 and H2 if k = 2.5 X 10-4 mol+ L S-1.

17. How will you calculate solubility product from molar solubility?

18. Give the oxidation and reduction half cell reaction taking place in the Daniel cell.

19. Corrosion of aluminum takes place at a much slower rate than iron. Give reason

20. Explain why Zn on reaction with dil. H2SOliberate hydrogen, whereas copper cannot?

21. Write a note on Ultrafilteration?

22. When phenol on treatement with Br2/H2O readily gives a precipitate of 2, 4, 6 - tribomo phenol.

23. How is glycerol obtained commercially? State its uses.

24. How can the following conversion be effected? (i) Phenol to phenolphthalein.

25. Explain the isomerism exhibited by carboxylic acids.

26. Predict the product when calcium ethanoate '" and calcicum methanoate are dry distilled. Explain the reaction.

27. Explain Levine and hauser acetylation.

28. What are amino add? Explain essential and non-essential amino acids.

29. Give the structure of sucrose.

30. How is Low density polyethene prepared?