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#### Important 5 Mark Book Back Questions (New Syllabus) 2020

12th Standard EM

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Chemistry

Time : 01:00:00 Hrs
Total Marks : 100

Part A

20 x 5 = 100
1. The selection of reducing agent depends on the thermodynamic factor: Explain with an example.

2. A hydride of 2nd period alkali metal (A) on reaction with compound of Boron (B) to give a reducing agent (C). identify A , B and C.

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

4. Why europium (II) is more stable than Cerium (II)?

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

6. What is crystal field stabilization energy (CFSE)?

7. Aluminium crystallizes in a cubic close packed structure. Its metallic radius is 125pm. calculate the edge length of unit cell.

8. Sodium metal crystallizes in bcc structure with the edge length of the unit cell 4.3X108.cm. calculate the radius of sodium atom.

9. The time for half change in a first order decomposition of a substance A is 60 seconds. Calculate the rate constant. How much of A will be left after 180 seconds?

10. Rate constant k of a reaction varies with temperature T according to the following Arrhenius equation  $logK=logA-\frac { { E }_{ a } }{ 2.303R } \left( \frac { 1 }{ R } \right)$
Where Ea is the activation energy. When a graph is plotted for log k Vs $\frac{1}{K}$ a straight line with a slope of -4000K is obtained. Calculate the activation energy

11. Write the expression for the solubility product of Ca3 (PO4)2

12. What is the pH of an aqueous solution obtained by mixing 6 gram of acetic acid and 8.2 gram of sodium acetate and making the volume equal to 500 ml. (Given: Ka for acetic acid is  $1.8\times10^{-5}$)

13. For the cell Mg (s) Mg2+(aq)||Ag2+(aq)|Ag(s), calculate the equilibrium constant at 250C and maximum work that can be obtained during operation of cell. Given : $E^{0}_{Mg^{2+}|Mg}$=-237V and $E^{0}|_{Ag^{2+}|Ag}$=0.80V.

14. Give three uses of emulsions.

15. Explain intermediate compound formation theory of catalysis with an example

16. How will you convert acetylene into n-butyl alcohol.

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

18. Indentify A,B and C
$\overset{SoCl_2}\longrightarrow A \overset{NH_3}\longrightarrow B\overset{LiAH_4}\longrightarrow (C)$

19. What are different types of RNA which are found in cell

20. Write a note on co –polymer