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#### Important 5 Mark Creative Questions (New Syllabus) 2020

12th Standard EM

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Chemistry

Time : 01:00:00 Hrs
Total Marks : 140

Part A

28 x 5 = 140
1. In the extraction of copper, explain the smelting process.

2. What is zone refining? Describe the principle involved in the purification of the metal by this method.

3. How are silicates classified? Give an example for each type of silicate.

4. Why is dioxygen a gas but sulphur a solid?

5. Howdoes sulphuric acid react with metals at various conditions

6. An element 'A' occupies group number 15 and period number 3. It reacts with chlorine: to giveBwhich further reacts with chlorine to giveCat 273K. Both Band Care chlorinating agents for organic compounds. C is a better chlorinating agent because it chlorinates metals also.Breacts with SO3and reduces it to SO2' B has a pyramidal shape. C has
trigonal bipyramidal shape by sp3d hybridisation. Identify the element A and the compounds B ' and C. Write the reactions.

7. Write a short note on the oxidation states of 3d series elements.

8. Give the postulates and limitation of Werner's theory of co-ordination compounds.

9. How are metal carbonyls classified depending on the number of metal atoms?

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

11. 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?

12. Calculate the pH of 0.1 M CH3COOH solution. Dissociation constant of acetic acid is 1.8 x 10-5M.

13. Calculate the pH of a buffer mixture which contains 7.5 gms if acetic acid and 10.25 gms of sodium acetate in 1 litre of the solution. Ka for acetic acid is 1.8 x 10-5.

14. Derive Henderson - Hasselbalch equation

15. Write the Nernst equation for the half cell Zn2+(aq)/ Zn(s)

16. Derive a relationship between dissociation constant Ka and molar conductivity ${ \Lambda }_{ m }$

17. Write the characteristics of catalysts.

18. Explain the electrical property of colloids! with a neat diagram.

19. Ail organic compound (A) C3H8O answers Lucas test within 5-10 minutes and on oxidation forms B (C3H6O). This on further oxidation forms C(C2H4O2) which gives effervescence with Na2 CO3" Balso undergoes iodoform reaction. Identify A) B) and C. Explain the conversion of A to Band C.

20. What is major product formed when 3,3-dimethyl-2-butanol is heated in the presence of H2SO4.

21. An organic compound (A) of molecular formula C3H8O2 is obtained as by-product in the manufacture of soap. Compound (A) on heating with P2O5 gives an unsaturated compound (B) of molecular formula C3H4O. Compound (A) with well cooled mixture of Conc.H2SO4 and fuming HNO3 form compound (C) which is an explosive. Identify A, B and C and explain the rection.

22. Draw resonance structures for the following
(i) CH3COO-
(ii)CH3CONH2
(iii) C6HsCHO
(iv) C6H5COO

23. Give two tests for aldehydes.

24. An organic compound (A) with molecular formula C3H6O undergoes iodoform reaction. Two molecules of compound (A) react with dry HCI to give compound (B) (C6H10O). Compound (B) reacts with one more molecule of compound (A) to give compound (C) (C9H14O). Identify (A), (B) and (C). Explain the reactions.

25. Draw a flow chart to show classification of nitro compound giving examples for each type.

26. How do primary, secondary and tertiary amines react with nitrous acid?

27. Explain the classification of hormones.

28. Explain the classification of polymers based on their structure and mode of synthesis.