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#### Public Model Question Paper Part-X 2019 - 2020

12th Standard EM

Reg.No. :
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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. In acid leaching process. the insoluble sulphide is converted into soluble sulphate and elemental_________

(a)

carbon

(b)

(c)

sulphur

(d)

zinc

2. Oxidation state of carbon in its hydrides

(a)

+4

(b)

-4

(c)

+3

(d)

+2

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 magnetic moment of Mn2+ ion is

(a)

5.92BM

(b)

2.80BM

(c)

8.95BM

(d)

3.90BM

5. A magnetic moment of 1.73BM will be shown by one among the following (NEET)

(a)

TiCl4

(b)

[CoCl6]4-

(c)

[Cu(NH3)4]2+

(d)

[Ni(CN)4]2-

6. The number of close neighbours in a body centred cubic lattice of identifical spheres is

(a)

6

(b)

4

(c)

12

(d)

8

7. The half life period of a radioactive element is 140 days. After 560 days , 1 g of element will be reduced to

(a)

$\left( \cfrac { 1 }{ 2 } \right) g$

(b)

$\left( \cfrac { 1 }{ 4 } \right) g$

(c)

$\left( \cfrac { 1 }{ 8 } \right) g$

(d)

$\left( \cfrac { 1 }{ 16 } \right) g$

8. Which of the following can act as lowery – Bronsted acid well as base?

(a)

HCl

(b)

SO42−

(c)

HPO42−

(d)

Br-

9. The hydrogen ion concentration of a buffer solution consisting of a weak acid and its salt is given by

(a)

$[{ H }^{ + }]={ K }_{ a }\frac { [Acid] }{ [Salt] }$

(b)

$[{ H }^{ + }]={ K }_{ a }[Salt]$

(c)

$[{ H }^{ + }]={ K }_{ a }[Salt]$

(d)

$[{ H }^{ + }]={ K }_{ a }\frac { [Acid] }{ [Salt] }$

10. Using the data given below fmd out the strongest reducing agent
${ E }_{ { Cr }_{ 2 }{ O }_{ 7 }^{ 2- } }^{ o }{ Cr }^{ 3+ }=1.33V{ ,E }_{ { Cl }_{ 2 }{ / }{ Cl }^{ - } }^{ o }=1.36V$
${ E }_{ { Mn }O_{ 4 }^{ - } }^{ 0 }/{ Mn }^{ 2+ }=1.51V,{ E }_{ { Cr }^{ 3+ }/Cr }^{ o }=-0.74V$

(a)

Cr

(b)

Cr3+

(c)

Cl-

(d)

Mn2+

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. Ethers are insoluble in water due to the

(a)

absence of co-ordinate bond

(b)

presence of co-ordinate bond

(c)

absence of H - bond

(d)

presence of H - bond

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. Which one of the following is a secondary amine?

(a)

aniline

(b)

diphenyl amine

(c)

see.butylamine

(d)

tert.butylamine

15. ______act as a shock absorber and act lubricant.

(a)

glycogen

(b)

Ribose

(c)

starch

(d)

hyaluronate

16. Part II

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

6 x 2 = 12
17. Name the various refming process

18. Give the uses of Borax

19. Give two uses of nitric acid

20. Calculate the magnetic moment of [Fe(H2O)6]2+, if atomic number of Fe is 26.

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

22. How will you determine the rate constant for the decomposition of nitrogen pentaoxide in CCI4.
Decomposition of nitrogen pentoxide in CCl4.

23. Discuss the Lowery – Bronsted concept of acids and bases.

24. Give the empirical relationship between molar conductance and concentration of the electrolyte.

25. Suggest a suitable reagent to prepare secondary alcohol with identical group using Grignard reagent.

26. Part III

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

6 x 3 = 18
27. What is liquation?

28. What is chromyl chloride test? Give equations.

29. How to predict the feasibility of a cell reaction?

30. What are enzymes? Write a brief note on the mechanism of enzyme catalysis.

31. Account for the following:
(a) Lower members of alcohols are soluble in water but higher members are not.
(b) Alcohols cannot be used as solvent for Grignard reagent.

32. 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.

33. Write a note on structure of amine.

34. Give the structure of α - D - glucose and β- D - glucose

35. Give examples for (i) addition polymer, (ii) Synthetic rubbers, (iii) Condensation polymers, (iv) formaldehyde resins.

36. Part IV

5 x 5 = 25
1. Complete the following reactions

ii) $C_6H_5-CHCH(OH)CH(CH_3)_2 \overset{ConH_2SO_4}\longrightarrow$

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. 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. An amorphous solid (A) burns in air to form a gas (B)which turns lime water milky. The gas is also produced as a byproduct during roasting of sulphide ore. This gas decolourises acidified aqueous KMnO4 solution and reduces Fe3+ to Fe2+. Identify the solid 'A' and the gas 'B' and write the reactions involved.

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

2. Write a note on Freundlich adsorption isotherm.

1. What are the general characteristics of solids?

2. How do nature of the reactant influence rate of reaction.

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

2. What is meant by stability of a co-ordination compound in solution? State the factors which govern stability of complexes.