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#### Public Model Question Paper Part-IV 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. Magnetic separation it is based on the difference in the_________ of the ore and the impurities.

(a)

magnetic properties

(b)

chemical properties

(c)

physical properties

(d)

melting point

2. Which of the following is not sp2 hybridised?

(a)

Graphite

(b)

graphene

(c)

Fullerene

(d)

dry ice

3. Repeated use of which one of the following fertilizers would increase the activity of the soil_______

(a)

Ammonium sulphate

(b)

Superphosphate of lime

(c)

Urea

(d)

Potassium nitrate

4. The actinoid elements which show the highest oxidation state of +7 are

(a)

Np, Pu ,Am

(b)

U, Fm, Th

(c)

U, Th, Md

(d)

Es, No, Lr

5. Which one of the following complexes is not expected to exhibit isomerism?

(a)

[Ni(NH3)4(H2O)2]2+

(b)

<>

(c)

[Co(NH3)5SO4]Cl

(d)

[Fe(en)3]3+

6. Which of the following cannot be regarded as molecular solid?

(a)

Silicon carbide

(b)

AIN

(c)

Diamond

(d)

All 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. Which will make basic buffer?

(a)

50 mL of 0.1M NaOH+25mL of 0.1M CH3 COOH

(b)

100 mL of 0.1M CH3COOH+100 mL of 0.1M NH4OH

(c)

100 mL of 0.1M HCl+200 mL of 0.1M NH4OH

(d)

100 mL of 0.1M HCl+100 mL of 0.1M NaOH

9. An acid is a substance that dissociates to give hydrogen ions in water.
The above concept of acids was proposed by ______________

(a)

Lewis

(b)

Arrhenius

(c)

Bronsted

(d)

Lowry

10. In Daniel cell, the charges developed by Zn/Zn2+ and Cu / Cu2+ are _________

(a)

positive, positive

(b)

negative, negative

(c)

positive, negative

(d)

negative, positive

11. The phenomenon observed when a beam of light is passed through a colloidal solution is

(a)

Cataphoresis

(b)

Electrophoresis

(c)

Coagulation

(d)

Tyndall effect

12. The functional isomer of n-propanol is _______

(a)

2-propanol

(b)

prop-en-ol

(c)

ethyl methyl ether

(d)

acetaldehyde

13. An alkene “A” on reaction with O3 and Zn - H2O gives propanone and ethanol in equimolar ratio. Addition of HCl to alkene “A” gives “B” as the major product. The structure of product “B” is

(a)

$Cl-{ CH }_{ 2 }-CH_{ 2 }-\overset { \overset { CH_{ 3 } }{ | } }{ \underset { \underset { CH_{ 3 } }{ | } }{ CH } }$

(b)

${ H }_{ 3 }C-{ CH }_{ 2 }-\overset { \overset { CH_{ 2 }Cl }{ | } }{ CH } -{ CH }_{ 3 }$

(c)

$\\ { H }_{ 3 }C-{ CH }_{ 2 }-\overset { \overset { CH_{ 3 } }{ | } }{ \underset { \underset { CH_{ 3 } }{ | } }{ C } } -{ CH }_{ 3 }$

(d)

${ H }_{ 3 }C-{ CH }-\overset { \overset { CH_{ 3 } }{ | } }{ \underset { \underset { Cl }{ | } }{ C } }$

14. Nitromethane condenses with acetaldehyde to give

(a)

nitro propane

(b)

1-nitro-2-propanol

(c)

2-nitro-1-propanol

(d)

3-nitro propanol

15. The ultimate product of hydrolysis of starch in the presence of dilute acid is

(a)

dextrin

(b)

maltose

(c)

maltase

(d)

glucose

16. Part II

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

6 x 2 = 12
17. Why should we have a ecofriendly metallurgical process?

18. Describe briefly allotropism in p- block elements with specific reference to carbon

19. How is SO2 an air pollutant?

20. What are anionic & cationic complex? Give an example.

21. What are point defects?

22. Rate of chemical reaction is not uniform throughout. Justify you answer:

23. What are lewis acids and bases? Give two example for each.

24. Higher the standard reduction potential lesser is corrosion. Give reason.

25. 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

26. Part III

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

6 x 3 = 18
27. What is meant by aluminotherrnitc process?

28. Account for the following:
(i) Cobalt (II) is stable in aqueous solution but in the presence of complexing reagents, it is easily oxidised.
(ii) The d1 configuration is very unstable in ions.

29. State Ohms law.

30. Peptising agent is added to convert precipitate into colloidal solution. Explain with an example.

31. Account for the following:
(I) Phenol does not get protonated readily.
(ii) Phenol, benzene diazonium chloride, NaOH solution gives red dye.

32. A carbonyl compound A having molecular formula C5H10O forms crystalline precipitate with sodium bisulphate and gives positive iodoform test. A does not reduce Fehling solution. XII Identify A.

33. An Organic compound (A) with molecular formula C6H7N gives (B) with HNO2 / HCI at 273 K. The aqueous solution of (B) on heating gives compound (C) which gives violet colour with netural FeCI3. Identify the compounds (A), (B) and (C) and write the equations.

34. Write note on oligosaccharides and polysaccharides with examples.

35. Write a short note on Antioxidants.

36. Part IV

5 x 5 = 25
1. Complete the following reactions
i) CH3- CH2 - OH $\overset { { P}{ Br_3 }{ } }{ \underset { {} }{ \longrightarrow } }$  A  $\overset { { aq.NaOH}{ }{ } }{ \underset { {} }{ \longrightarrow } }$ B $\overset { { Na}{ } }{ \underset { {} }{ \longrightarrow } }$
ii) C6H5- OH  $\overset { { Zndert}{ } }{ \underset { {} }{ \longrightarrow } }$ A $\overset { { CH_3}{Cl}{ } }{ \underset { {Anhydrs}{AlCl_3} }{ \longrightarrow } }$ B $\overset { { acid}{K MnO_4}{ } }{ \underset { {} }{ \longrightarrow } }$ C

2. An organic compound (A) of molecular formula C7H6O is not reduced by Fehling's solution but will undergo Cannizzaro reaction. Compound (A) reacts with aniline to give compound (B). Compound (A) also reacts with Cl2 in the presence of catalyst to give compound (C). Identify (A (B) and (C) and explain the reactions.

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

2. Name the method to deduce the charge of the sol particle. Explain it with a neat diagram.

1. Write note on impurity defect?

2. The activation energy of a reaction is 225 k Cal mol-1 and the value of rate constant at 40°C is 11.8X10-6s-1Calculate the frequency factor, A.

1. How are materials classified based on their magnetic properties?

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. A hydride of 2nd period alkali metal (A) on reaction with compound of Boron (B) to give a reducing agent (C). identify A , B and C.

2. Explain the oxidising and reducing property of SO2·