#### 12th Standard English Medium Chemistry Reduced Syllabus Public Exam Model Question Paper - 2021

12th Standard

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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. Name the process by which elements such as germanium, silicon and galium are refined.

(a)

Vapour phase method

(b)

Electrolytic refining

(c)

Zone refining

(d)

Van-Arkel method

2. The geometry at which carbon atom in diamond are bonded to each other is

(a)

Tetrahedral

(b)

graphene

(c)

Fullerene

(d)

dry ice

3. Pick the wrong one among the following

(a)

F2 - Yellow

(b)

Br2 - Red

(c)

Cl2 - Colourless

(d)

I2- Violet

4. Among the transition metals of 3d series, the one that has highest negative $\left( \frac { M^{ 2+ } }{ M } \right)$ standard electrode potential is

(a)

Ti

(b)

Cu

(c)

Mn

(d)

Zn

5. Which one of the following will give a pair of enantiomorphs?

(a)

[Cr(NH3)6][Co(CN)6]

(b)

[Co(en)2Cl2]cl

(c)

[pt(NH3)4][ptcl4]

(d)

[Co(NH3)4Cl2]NO2

6. Schottky defects contains

(a)

Cation vacancies only

(b)

Cation vacancies and interstitial cations

(c)

Equal number of cation and anion vacancies

(d)

Anion vacancies and interstitial anions

7. In a homogeneous reaction $A\longrightarrow B+C+D$ the initial pressure was P0 and after time t it was P. expression for rate constant in terms of P0, P and t will be

(a)

$k=\left( \cfrac { 2.303 }{ t } \right) log\left( \cfrac { 2{ P }_{ 0 } }{ { 3P }_{ 0 }-P } \right)$

(b)

$k=\left( \cfrac { 2.303 }{ t } \right) log\left( \cfrac { { 2P }_{ 0 } }{ { P }_{ 0 }-P } \right)$

(c)

$k=\left( \cfrac { 2.303 }{ t } \right) log\left( \cfrac { 3{ P }_{ 0 }-P }{ 2P_{ 0 } } \right)$

(d)

$k=\left( \cfrac { 2.303 }{ t } \right) log\left( \cfrac { 2{ P }_{ 0 } }{ { 3P }_{ 0 }-2P } \right)$

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

(a)

HCl

(b)

SO42−

(c)

HPO42−

(d)

Br-

9. The conjugate base of HCIO is _________

(a)

ClO-

(b)

Cl-

(c)

H2ClO+

(d)

CIO

10. 1 mho is equal to

(a)

1 siemen

(b)

1 second

(c)

1 ohm

(d)

none of the above

11. Which one of the following characteristics are associated with adsorption?

(a)

$\Delta$G and $\Delta$H are negative but $\Delta$S is positive

(b)

$\Delta$G and $\Delta$S are negative but $\Delta$H is positive

(c)

$\Delta$G is negative but $\Delta$H and $\Delta$S are positive

(d)

$\Delta$G,$\Delta$H and $\Delta$S all are negative.

12. 1-Propanol and 2- propanol can be best distinguished by

(a)

oxidation with KMnO4 followed by reaction with Fehling solution

(b)

oxidation with acidic dichromate followed by reaction with Fehling solution

(c)

oxidation by heating with copper followed by reaction with Fehling solution

(d)

oxidation with concentrated H2SO4 followed by reaction with Pehling solution

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

(a)

nucleophilic substitution

(b)

electrophilic substitution

(c)

(d)

14. CH3NO2+6[H] $\underrightarrow { X? }$ CH3NH2+2H2O. 'X' is

(a)

Sn/HCI

(b)

Zn/NH4CI

(c)

Glucose + NaOH

(d)

Na3A5O3/NaOH

15. Carbohydrates are

(a)

polyhydroxy aldehydes

(b)

polyhydroxy ketones

(c)

polyhydroxy acids

(d)

both (a) and (b)

16. Part II

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

6 x 2 = 12
17. Discuss the process of roasting with suitable example.

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

19. Although $\triangle$H of fluorine is less negative than that of chlorine, but fluorine is a stronger oxidising agent than chlorine, why?

20. Define coordination number.

21. What are point defects?

22. The decomposition reaction of ammonia gas on platinum surface has a rate constant R = 2.5 x 10-4mol L-1. What is the order of the reaction.

23. Define solubility product

24. What is a electro chemical cell?

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

26. Part III

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

6 x 3 = 18
27. What is coupling of reaction? How is it useful in metallurgy?

28. Explain the oxidising property of KMnO4 in alkaline medium

29. Write the electrochemical cell for the overall cell reaction.
Zn(S)+2AgNO3 ⟶ 2Ag(S) +Zn(NO3)2

30. What happens when a colloidal sol of Fe(OH)3 and AS2O3 are mixed?

31. Halo alkane are easily prepared from alcohols while aryl halides cannot be prepared from phenol.- Justify.

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

33. An organic compound 'A' on reduction gives compound 'B' which on reaction with trichloromethane and caustic potash forms 'C'. Compound 'C' on catalytic reduction given N-methyl benzenamine. Identify A, B and C and write the reactions involved.

34. Name two water soluble vitamins, their sources, function and diseases caused due to their deficiency in diet.

35. Write the preparation of neoprene and give its use.

36. Part IV

5 x 5 = 25
1. Write a note on zeolites.

2. Explain the structure of inter halogen compounds

1. Why is there a variation of atomic andionic size as we move from Sc to Zn?

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

1. Write note on impurity defect?

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

1. Solubility product of Ag2 CrO4 4 is $1\times10^{-12}$.What is the solubility of Ag2 CrO4 in 0.01M AgNO3 solution?

2. Write a note on phase transfer catalysis.

1. Phenol is distilled with Zn dust followed by friedel – crafts alkylation with prophyl chloride to give a compound B, B on oxidation gives (c) Indentify A,B and C.

2. 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.