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#### Important 2 Mark Book Back Questions (New Syllabus) 2020

12th Standard EM

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Chemistry

Time : 01:00:00 Hrs
Total Marks : 32

Part A

16 x 2 = 32
1. Boron does not react directly with hydrogen. Suggest one method to prepare diborane from BF3.

2. Explain why fluorine always exhibit an oxidation state of -1?

3. Justify the position of lanthanides and actinides in the periodic table.

4. [CuCl4]2- exists while [Cul4]2- does not exist why?

5. Explain briefly seven types of unit cell

6. Describe the graphical representation of first order reaction.

7. What is the order with respect to each of the reactant and overall order of the following reactions?
a) 5Br-(aq)+BrO3-(aq)+6H+(aq) ➝3Br2(l)+3H2O(l)
The experimental rate law is
Rate = k [Br−][BrO3][H+]2
b) CH3CHO(g)$\overset { \Delta }{ \longrightarrow }$ CH4(g)+CO(g) the experimental rate law is
Rate =K[CH3CHO]$\frac{3}{2}$

8. The concentration of hydroxide ion in a water sample is found to be 2.5×10-6M. Identify the nature of the solution.

9. Why does conductivity of a solution decrease on dilution of the solution

10. A conductivity cell has two platinum electrodes separated by a distance 1.5 cm and the
cross sectional area of each electrode is 4.5 sq cm. Using this cell, the resistance of 0.5 N electrolytic solution was measured as 15 Ω . Find the specific conductance of the solution.

11. Differentiate physisorption and chemisorption

12. Predict the major product, when 2-methyl but -2-ene is converted into an alcohol in each of the following methods.
(i) Acid catalysed hydration
(ii) Hydroboration
(iii) Hydroxylation using bayers reagent

13. State the laws of reflection

14. Identify compounds A,B and C in the following sequence of reactions.
i) ${ C }_{ 6 }{ H }_{ 5 }NO_{ 2 }\overset { Fe/HCL }{ \longrightarrow } A\overset { HN{ O }_{ 2 } }{ \underset { 273K }{ \longrightarrow } } B\overset { { C }_{ 6 }{ H }_{ 5 }OH }{ \longrightarrow } C$
ii) ${ C }_{ 6 }{ H }_{ 5 }N_{ 2 }cl\overset { CuCN }{ \longrightarrow } A\overset { H_{ 2 }O/H^{ + } }{ \longrightarrow } B\overset { NH_3 }{ \longrightarrow } C$

iii) ${ C }{ H }_{ 3 }{ C }{ H }_{ 2 }I\overset { NaCN}{ \longrightarrow } A\overset {OH^-}{ \underset {Partial hydrolysis}{ \longrightarrow } } B\overset {NaOH+Br_2 }{ \longrightarrow } C$
iv) ${ C }{ H }_{ 3 }NH_{ 2 }\overset { CH_3 Br }{ \longrightarrow } A\overset { CH_{ 3 }COCl}{ \longrightarrow } B\overset { B_2H_6 }{ \longrightarrow } C$
v) ${ C }_{ 6 }{ H }_{ 5 }NH_{ 2 }\overset { (CH_{ 3 }CO)_{ 2 }O }{ \underset { Pyridine }{ \longrightarrow } } A\overset { HNO_{ 3 } }{ \underset { H_{ 2 }SO_{ 4 },288K }{ \longrightarrow } } B\overset { { H }_{ 2 }O/{ H }^{ + } }{ \longrightarrow C }$
vi)

vii) ${ C }{ H }_{ 3 }CN_{ 2 }NC\overset { HgO }{ \longrightarrow } A\overset { H_{ 2 }O }{ \longrightarrow } B\overset { i)\quad NaN{ O }_{ 2 }/HCL }{ \underset { ii){ \quad H }_{ 2 }O }{ \longrightarrow } }$

15. Name the Vitamins whose deficiency cause i) rickets ii) scurvy

16. Write a note on synthetic detergents