#### 12th Standard English Medium Chemistry Reduced Syllabus Five mark Important Questions with Answer key - 2021(Public Exam )

12th Standard

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Chemistry

Time : 02:00:00 Hrs
Total Marks : 125

Part A

25 x 5 = 125
1. Give the limitations of Ellingham diagram

2. Explain refming of titanium by Van-Arkel method.

3. Deduce the oxidation number of oxygen in hypofluorous acid – HOF.

4. Give a detailed account on allotropes of sulphur.

5. Explain the bleaching action of Chlorine.

6. Describe the variable oxidation state of 3d series elements.

7. Why is there a variation of atomic andionic size as we move from Sc to Zn?

8. On the basis of VB theory explain the nature of bonding in [CoC2O4)3]3-

9. What are the salient feature of crystal field theory?

10. Sodium metal crystallizes in bcc structure with the edge length of the unit cell 4.3 x 108.cm. calculate the radius of sodium atom.

11. How can you determine the atomic mass of an unknown metal if you know its density and the dimension of its unit cell? Explain.

12. The activation energy of a reaction is 22.5 k Cal mol-1 and the value of rate constant at 40°C is 1.8 x 10-5s-1Calculate the frequency factor, A.

13. The conversion of molecules x to y follows second order kinetics. Its concentration of x is increased to three times how will it affect the rate of formation of y?
For the reaction x ➝ y as it follows second order kinetics wherefore the rate of formation of y?

14. Will a precipitate be formed when 0.150 L of 0.1M Pb(NO3)2 and 0.100L of 0.2 M NaCl are mixed?$K_{sp}\quad(PbCl_{2})=1.2\times10^{-5}$.

15. Calculate the pH of 0.1 M acetic acid if its ionisation constant Ka = 1.8 X 10-5.

16. 8.2$\times$1012 litres of water is available in a lake. A power reactor using the electrolysis of water in the lake produces electricity at the rate of    2$\times$106 Cs−1 at an appropriate voltage. How many years would it like to completely electrolyse the water in the lake. Assume that there is no loss of water except due to electrolysis.

17. To one molar solution of a trivalent metal salt, electrolysis was carried out and 0.667 M was the concentration remaining after electrolysis. Calculate the quantity of electricity passed.

18. Write a note on catalytic poison

19. Give the special characteristics of enzyme catalysed reactions.

20. Phenol is distilled with Zn dust followed by friedel – crafts alkylation with prophyl chloride to give a compound B, B on oxidation gives (c) Indentify A,B and C.

21. An aromatic hydrocarbon A reacts with propene in the presence of anhydrous AlCl3 to give a compound B with a molecular formula C9H12 Further compound B undergoes oxidation in the, presence of air to give hydrogenperoxide C. Compound C decomposes in HCI acid solution to give compound D and acetone. Identify A, B, C and D. Explain the reactions,

22. Write the structure of the major product of the aldol condensation of benzaldehyde with acetone.

23. Discuss the mechanism of aldol condensation.

24. A Monoobromoderivative (A) on treatment with KCN followed by acid hydrolysis and heating gives a monobasic acid (B) along with liberation of CO2 . (B) on heating with liquid ammonia followed by treating with Br2 /KOH  gives (c) which on treating with NaNO2 and HCl at low temperature followed by oxidation gives a monobasic acid (D) having molecular mass 74. Identify A to D.

25. How is terylene prepared?