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#### Sample 3 Mark Book Back Questions (New Syllabus) 2020

12th Standard EM

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Chemistry

Time : 01:00:00 Hrs
Total Marks : 48

Part A

16 x 3 = 48
1. Explain the electrometallurgy of aluminium

2. Write a short note on hydroboration

3. Give the uses of sulphuric acid.

4. Explain why Cr2+ is strongly reducing while Mn3+ is strongly oxidizing.

5. What is linkage isomerism? Explain with an example

6. Why ionic crystals are hard and brittle?

7. Write Arrhenius equation and explains the terms involved

8. (ii) The half life of a first order reaction x ⇾products is 6.932 x 104 s at 500K. What percentage of x would be decomposed on heating at 500K for 100 min. (e0.06 = 1.06).

9. Calculate the pH of 0.1M CH3COOH solution. Dissociation constant of acetic acid is $1.8\times10^{-5}$.

10. 0.1M NaCl solution is placed in two different cells having cell constant 0.5 and 0.25cm-1 respectively. Which of the two will have greater value of specific conductance.

11. What happens when a colloidal sol of Fe(OH)3 and AS2O3 are mixed?

12. Writes the chemical equation for Williamson synthesis of 2-ethoxy – 2- methyl pentane  starting from ethanol and 2 – methyl pentan -2-ol

13. An alkene (A) on ozonolysis gives propanone and aldehyde (B). When (B) is oxidised (C) is obtained. (C) is treated with BriP gives (D) which on hydrolysis gives (E). When propanone is treated with HCN followed by hydrolysis gives (E). Identify A) B) C) D and E.

14. Identify A,B,C and D
CH3- NO2 $\overset { { L }_{ 1 }{AlH }_{ 4 } }{ \underset { {} }{ \longrightarrow } }$ A  $\overset { { 2CH_3 }{Ch_2Br } }{ \underset { {} }{ \longrightarrow } }$ B $\overset { {H}_{ 2 }{SO}_{ 4 } }{ \underset { {} }{ \longrightarrow } }$ C

15. What are reducing and non – reducing sugars?

16. Which sweetening agent are used to prepare sweets for a diabetic patient?