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Public Model Question Paper Part-IX 2019 - 2020

12th Standard EM

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Chemistry

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

Part I

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 of the following is incorrect with respect to metallurgy of iron in the blast furnace?

(a)

Zone of combustion : $C+{ O }_{ 2 }\rightarrow { CO }_{ 2 }$

(b)

Zone of heat absorption : ${ CO }_{ 2 }\rightarrow C+{ O }_{ 2 }$

(c)

Zone of slag formation : $CaO+{ SiO }_{ 2 }\rightarrow CaSiO_{ 3 }$

(d)

Zone of reduction : ${ Fe }_{ 2 }{ O }_{ 3 }3C\rightarrow 3CO+2Fe$

2.  Column-I Column-II A Borazole 1 B(OH)3 B Boric acid 2 B3N3H6 C Quartz 3 Na2[B4O5(OH)4]8H2O D Borax 4 SiO2
(a)
 A B C D 2 1 4 3
(b)
 A B C D 1 2 4 3
(c)
 A B C D 1 2 4 3
(d)

None of these

3. Which among the following ion is not formed?

(a)

F3-

(b)

C13-

(c)

Br3-

(d)

I3-

4. Which one of the following statements related to lanthanons is incorrect?

(a)

Europium shows +2 oxidation state

(b)

The basicity decreases as the ionic radius decreases from Pr to Lu.

(c)

All the lanthanons are much more reactive than aluminium

(d)

Ce4+ solutions are widely used as oxidising agents in volumetric analysis.

5. The sum of primary valance and secondary valance of the metal M in the complex [M(en)2(Ox)]Cl isL

(a)

3

(b)

6

(c)

-3

(d)

9

6. ABAB type of packing is called _________.

(a)

hexagonal close packing

(b)

cubic close packing

(c)

tetragonal close packing

(d)

none of the above

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. Dissociation constant of NH4OH is 1.8 x 10-5  the hydrolysis constant of NH4Cl would be

(a)

1.8 ×10-19

(b)

5.55 ×10-10

(c)

5.55 ×10-5

(d)

1.80 ×10-5

9. ${ X }_{ m }{ Y }_{ n(s) }\overset { { H }_{ 2 }O }{ \rightleftharpoons } { mX }_{ (aq) }^{ n+ }+{ nY }_{ (aq) }^{ m- }$

(a)

${ [{ X }^{ n+ }] }^{ m }{ [Y^{ m- }] }^{ n }$

(b)

${ [X }^{ n+ }][{ Y }^{ m- }]$

(c)

${ [{ X }^{ n+ }] }^{ m }/{ [Y^{ m- }] }^{ n }$

(d)

${ [X }^{ n+ }]/[{ Y }^{ m- }]$

10. A device in which spontaneous chemical reaction generates electric current.

(a)

Galvanic cell

(b)

Voltaic cell

(c)

Daniel cell

(d)

All the above

11. Which one of the following is an example for homogeneous catalysis?

(a)

manufacture of ammonia by Haber’s process

(b)

manufacture of sulphuric acid by contact process

(c)

hydrogenation of oil

(d)

Hydrolysis of sucrose in presence of all HCl

12. The IUPAC name for isobutyl alcohol is _______

(a)

2-methyl-l-propanol

(b)

2-methyl-l-butanol

(c)

2,2-dimethyl-2-propanol

(d)

1,1-dimethyl- 2-butanol

13. The formation of cyanohydrin from acetone is an example of

(a)

nucleophilic substitution

(b)

electrophilic substitution

(c)

(d)

14. The intermediate formed in the nitration of benzene is _________

(a)

Arenium ion

(b)

Carbanion

(c)

Oxonium ion

(d)

Nitrite ion

15. The sugar unit present in nucleic acid is___________

(a)

a hexose

(b)

tetrose

(c)

pentose

(d)

glucose

16. Part II

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

6 x 2 = 12
17. What are the different methods of concentration of ores?

18. Give the uses of Borax

19. Give reason for the following:
F2 is more reactive than CIF3 but CIF3 is more reactive than Cl2

20. What are enantiomers?

21. Distinguish between hexagonal close packing and cubic close packing.

22. Mention the factors that affected the rate of a chemical reaction.

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. What is standard reduction potential Eo?

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. What are the applications of the Ellingham diagram?

28. What are redox reactions?

29. Give the oxidation and reduction half cell reaction taking place in the Daniel cell.

30. Addition of Alum purifies water. Why?

31. Complete the following equations by writing the missing A, B, C, D etc.,

32. What is the action of HCN on
(i) propanone
(ii) 2,4-dichlorobenzaldehyde.

33. Aniline reacts with Br2/H2O to give a tribromo derivative. How would you convert aniline to get a monobromo derivate?

34. Give example of epimers.

35. How is Buna - N prepared? Give its use.

36. Part IV

5 x 5 = 25
1. 0.44g of a monohydric alcohol when added to methyl magnesium iodide in ether liberates at STP 112 cm3 of methane with PCC the same alcohol form a carbonyl compound that answers silver mirror test. Identify the compound.

2. An aromatic aldehyde (A) of molecular formula C7H6O which has the smell of bitter almonds on treatment with (CH3CO)2O and CH3COONa to give compound (B) which is an aromatic unsaturated add. (A) also reacts with (A) in the presence of ale. KCN to give dimer (C). Identify (A), (B) and (C). Explain the reactions.

1. Ksp of AgCl is $1.8\times10^{-10}$. Calculate molar solubility in 1 M AgNO3

2. Write any five applications of colloids in day - to day life.

1. What are stoichiometric defects in ionic solids? Explain

2. The rate constant for a first order reaction is 1.54x 10-3 s-1. Calculate its half life time.

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

2. For the complex [NiCI4]2- write (i) the IUPAC name (ii) The hybridisation type (iii) The shape of the complex

1. A double salt which contains fourth period alkali metal (A) on heating at 500K gives (B). aqueous solution of (B) gives white precipitate with BaCl2 and gives a red colour compound with alizarin. Identify A and B.

2. Explain the oxidising and reducing property of SO2·