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#### Public Model Question Paper 2019 - 2020

12th Standard EM

Reg.No. :
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Chemistry

Time : 02:45:00 Hrs
Total Marks : 70

Part I

Answer all the questions.

Choose the most suitable answer from the given four alternatives and write the option code with the corresponding answer.

15 x 1 = 15
1. Which metal is used for extraction of Au and Ag and also for galvanisation of iron objects?

(a)

Mg

(b)

Zn

(c)

Cr

(d)

Co

2. The basic structural unit of silicates is (NEET)

(a)

$\left( SiO_{ 3 } \right) ^{ 2- }$

(b)

$\left( SiO_{ 4 } \right) ^{ 2- }$

(c)

$\left( Sio \right) ^{ - }$

(d)

$\left( SiO_{ 4 } \right) ^{ 4- }$

3. Thr hybridisation and shape of SF6 is respectively?

(a)

sp3d2,square planar

(b)

sp3d2,octahedral

(c)

sp3d see-saw

(d)

sp3d,trigonal bipyramindal

4. Which of the following oxidation states is most common among the lanthanoids?

(a)

4

(b)

2

(c)

5

(d)

3

5. A complex has a molecular formula MSOCl. 6HO42.The aqueous solution of it gives white precipitate with Barium chloride solution and no precipitate is obtained when it is treated with silver nitrate solution. If the secondary valence of the metal is six, which one of the following correctly represents the complex?

(a)

[M(H2O)4Cl]SO42H2O

(b)

[M(H2O)6]SO4

(c)

[M(H2O)5Cl]SO4H2O

(d)

[M(H2O)3Cl]SO4.3H2O

6. In a solid, the cation is missing from the lattice and is found in an interstital position. The defect is __________.

(a)

Metal excess

(b)

p type

(c)

Schottky

(d)

Frenkel

7. For a first order reaction A ⟶ B the rate constant is x min−1. If the initial concentration of A is 0.01M , the concentration of A after one hour is given by the expression.

(a)

001. e−x

(b)

1 x 10-2(1-e-60x)

(c)

(1x10-2)e-60x

(d)

none of these

8. If the solubility product of lead iodide is 3.2 ×10-8 , its solubility will be

(a)

2×10-3M

(b)

4×10-4M

(c)

1.6 ×10-5M

(d)

1.8 ×10-5M

9. The solution whose pH is maintained constant even upon the addition of small amounts of acid or base is called ________

(a)

acidic solution

(b)

basic solution

(c)

buffer solution

(d)

true solution

10. The process in which chemical change occurs on passing electricity is termed as ______

(a)

neutralisatio

(b)

hydrolysis

(c)

electrolysis

(d)

ionisation

11. Fog is colloidal solution 0 of

(a)

solid in gas

(b)

gas in gas

(c)

liquid in gas

(d)

gas in liquid

12. Which among the following reagent is not used to differentiate ethanol and phenol?

(a)

neutral FeCl3

(b)

C6H5N2CI

(c)

NaOH

(d)

anhy ZnCl2

13. Reaction of acetone with one of the following reagents involves nucleophilic addition followed by elimination of water. The reagent is

(a)

Grignard reagent

(b)

Sn / HCl

(c)

hydrazine in presence of slightly acidic solution

(d)

hydrocyanic acid

14. Which among the following exists as zwitter ion?

(a)

sulphanilic acid

(b)

salicylic acid

(c)

acetanilide

(d)

all the above

15. Pick out the odd one.

(a)

Wax

(b)

Starch

(c)

Glucose

(d)

Fructose

16. Part II

Answer any 6 questions. Question no. 24 is compulsory.

6 x 2 = 12
17. Write the two similarities between calcination and roasting.

18. What is catenation ? describe briefly the catenation property of carbon

19. Discuss the oxidising power of fluorine

20. Give the geometry and magnetic character of [NiCI4]2-

21. What are point defects?

22. Why is instantaneous rate preferred over average rate?

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

24. Define conductance. Give its unit

25. Can we use nucelophiles such as NH3,CH3- for the Nucleophilic substitution of alcohols

26. Part III

Answer any 6 questions. Question no. 33 is compulsory.

6 x 3 = 18
27. Explain alkali leaching in the extraction of aluminum,

28. Complete the following reactions?
i) Cr2 + 2e-
ii) Mn2+ + 2e- ⟶
iii) Fe2+ + 2e
iv) CO2+ + 2e-

29. Write the reactions taking place in anode and cathode of a mercury button cell. Give the over all redox reaction of the cell with the emf generation

30. Describe some feature of catalysis by Zeolites.

31. Give chemical tests to distinguish between propan-2-ol and 2-methyl-propan-2-ol.

32. Identify A) B)C and D

33. How can the following conversion be effected?
i) Nitrobenzene to anisole
ii) Chloro benzene to phenyl hydrazine
iii)  Aniline to benzoic acid
iv) Benzene diazonium chloride to ehtyl benzene.

34. Amino acids are amphoteric in nature. Explain.

35. Write a short note on Antioxidants.

36. Part IV

Answer all the questions.

5 x 5 = 25
1. Justify the following statement.
"Elements of the first transition series possess many properties different from those of heavier transition elements".

2. Compound (A) of molecular formula C7H5when treated with air in presence of V2O5 at 773 K gives a compound (B) of molecular formula C7H6O, which has the smell of bitter almonds. Alkaline KMnO4 oxidisescompound (B) to (C) of molecular formula C7H6Or Compound (B) on treatment with N2H4and KOH gives back compound (A). Identify (A), (B) & (C) and explain the reactions.

1. What are the general characteristics of solids?

2. The half life of the homogeneous gaseous reaction SO2Cl2 → SO2 + Cl2 which obeys first order kinetics is 8.0 minutes. How long will it take for the concentration of SO2Cl2 to be reduced to 1% of the initial value?

1. Write a note on zeolites.

2. Indicate the types of isomerism exhibited by the following complexes and draw the structures for these isomers.
(i) K[Cr(H2O)2 (C2O4)2] (ii) [Co(en)3]CI3 (iii) [Co(NH3)5(NO2)](NO3)2
(iv) [Pt (NH3)(H2O)CI2]

1. Account for the following:
(i) Reducing character decreases from SO2 to TeO2.
(ii) Xenon forms compounds with fluorine and oxygen only.

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

1. Write the expression for the solubility product of Hg2Cl2 .

2. Identify A,B,C,D and write the compelete equation