#### 12th Standard Chemistry English Medium Reduced Syllabus Model Question paper With Answer Key - 2021 Part - 1

12th Standard

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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. Zinc is obtained from ZnO by

(a)

Carbon reduction

(b)

Reduction using silver

(c)

Electrochemical process

(d)

Acid leaching

2. In the electrolytic refining of copper, which one of the following is used as anode?

(a)

Pure copper

(b)

Impure copper

(c)

Carbon rod

(d)

Platinum electrode

3. The blistered appearance of Cu obtained from the reverberatory furance is due to evolution of

(a)

CO2 gas

(b)

S02 gas

(c)

NO2

(d)

Due to evaporation of volatile materials

4. Assertion : bond dissociation energy of fluorine is greater than chlorine gas
Reason: chlorine has more electronic repulsion than fluorine.
Codes:
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion
(c) Assertion is true but reason is false
(d) Both assertion and reason are false

(a)

Both assertion and reason are true and reason is the correct explanation of assertion.

(b)

Both assertion and reason are true but reason is not the correct explanation of assertion

(c)

Assertion is true but reason is false

(d)

Both assertion and reason are false

5. Which of the following d block element has half filled penultimate d sub shell as well as half filled valence sub shell?

(a)

Cr

(b)

Pd

(c)

Pt

(d)

none of these

6. A complex in which the oxidation number of the metal is zero is

(a)

K4[fe(CN)6]

(b)

[Fe(CN)3(NH3)5]

(c)

[Fe(CO)5]

(d)

both (b) and (c)

7. The vacant space in bcc lattice unit cell is

(a)

48%

(b)

23%

(c)

32%

(d)

26%

8. For a first order reaction, the rate constant is 6.909 min-1.the time taken for 75% conversion in minutes is

(a)

$\left( \cfrac { 3 }{ 2 } \right) { log }^{ 2 }$

(b)

$\left( \cfrac { 2 }{ 3 } \right) log2$

(c)

$\left( \cfrac { 3 }{ 2 } \right) log\left( \cfrac { 3 }{ 4 } \right)$

(d)

$\left( \cfrac { 2 }{ 3 } \right) log\left( \cfrac { 4 }{ 3 } \right)$

9. The solubility of BaSO4 in water is 2.42 ×10-3gL-1 at 298K. The value of its solubility product(Ksp) will be (Given molar mass of BaSO4 =233g mol 4-1)

(a)

1.08 ×10-14mol2L-2

(b)

1.08 ×10-12mol2L-2

(c)

1.08 ×10-10mol2L-2

(d)

1.08 ×10-8mol2L-2

10. Among the following cells
I) Leclanche cell
II) Nickel – Cadmium cell
III) Lead storage battery
IV) Mercury cell
Primary cells are

(a)

I and IV

(b)

I and III

(c)

III and IV

(d)

II and III

11. Statement :
To stop bleeding from an injury, ferric chloride can be applied. Which comment about the statement is justified?

(a)

It is not true, ferric chloride is a poison.

(b)

It is true, Fe3+ ions coagulate blood which is a negatively charged sol

(c)

It is not true; ferric chloride is ionic and gets into the blood stream.

(d)

It is true, coagulation takes place because of formation of negatively charged sol with Cl-.

12. Assertion : Phenol is more acidic than ethanol
Reason: Phenoxide ion is resonance stabilized
Codes:
(a) if both assertion and reason are true and reason is the correct explanation of assertion.
(b) if both assertion and reason are true but reason is not the correct explanation of assertion.
(c) assertion is true but reason is false
(d) both assertion and reason are false.

(a)

if both assertion and reason are true and reason is the correct explanation of assertion.

(b)

if both assertion and reason are true but reason is not the correct explanation of assertion.

(c)

assertion is true but reason is false

(d)

both assertion and reason are false.

13. CH3Br $\overset { KCN }{ \longrightarrow } (A)\overset { { H }_{ 2 }{ O }^{ + } }{ \longrightarrow } (B)\overset { { PCl }_{ 5 } }{ \longrightarrow }$ (C) product (c) is

(a)

acetylchloride

(b)

chloro acetic acid

(c)

$\alpha$- chlorocyano ethanoic acid

(d)

none of these

14. C6H5NO2 $\overset { Fe/Hel }{ \longrightarrow } A\overset { { NaNO }_{ 2 }/HCl }{ \underset { 273K }{ \longrightarrow } } B\overset { { H }_{ 2 }O }{ \underset { 283 }{ \longrightarrow } } C\quad 'C'is$

(a)

C6H5- OH

(b)

C6H5-CH2OH

(c)

C6H5- COH

(d)

C6H5NH2

15. The central dogma of molecular genetics states that the genetic information flows from

(a)

Amino acids Protein DNA

(b)

DNA Carbohydrates Proteins

(c)

DNA RNA Proteins

(d)

DNA RNA Carbohydrates

1. Part II

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

9 x 2 = 18
16. Write a note on Thrope nitrile condensation

17. List the expected products of hydrolysis of lactose.

18. The two strands in DNA are not identical but are complementary explain.

19. Give an example of a macromolecule chosen as drug targets.

20. Explain the terms.
(i) Antagonists drugs
(ii) Agonist drugs.

21. What are antipyretic?

22. What are soaps?

23. What is Condensation polymerisation?

24. Explain why chloroform is not used as an anaesthetic.

1. Part III

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

9 x 3 = 27
25. What happens to boranes at high temperatures?

26. Complete the following equations.
(i) Cr2O72- + 2OH-
(ii) MnO4- + 4H+ + 3e- ⟶

27. What is linkage isomerism? Explain with an example

28. Explain Schottky defect.

29. Explain AAAA and ABABA and ABCABC type of three dimensional packing with the help of neat diagram.

30. Why are solids rigid?

31. A reaction is second order with respect to a reactant. How is the rate of reaction affected if the concentration of the reactant is
(i) doubled (ii) reduced to half

32. Explain the IUPAC convention of representing a Galvanic cell

33. Arrange the following
i. In increasing order of solubility in water, C6H5 NH2,(C2H5)2 NH,C2H5NH2
ii. In increasing order of basic strength
a) aniline, p- toludine and p – nitroaniline
b) C6H5 NH2,C6H5 NHCH3,C6H5NH2 ,p-Cl-C6- H4-NH2
iii. In decreasing order of basic strength in gas phase
(C2H5)NH2 ,(C2H5)NH, (C2H5)5N and NH3
iv. In increasing order of boiling point
C6H5OH, (CH3)2NH, C2H5NH2
v. In decreasing order of the pKb values
C2H5NH2, C6H5NHCH3.(C2H5) NH and CH3NH2
vi. Increasing order of basic strength
C2H5NH2,C6H5NH(CH3)2 ,(C2H5)2 NH and CH3NH2
vii. In decreasing order of basic strength

1. Part IV

Answer all the questions.

10 x 5 = 50
34. How will you convert boric acid to boron nitride?

35. CO is a reducing agent . justify with an example.

36. Distinguish between diamond and graphite.

37. Why europium (II) is more stable than Cerium (II)?

38. Predict which of the following will be coloured in aqueous solution Ti2+ , V3+ Sc4+, Cu+ ,Sc3+, Fe3+, Ni2+ and Co3+

39. KF crystallizes in fcc structure like sodium chloride. calculate the distance between K+ and F in KF.( given : density of KF is 2483. gcm-3)

40. Write the expression for the solubility product of Ca3 (PO4)2

41. Calculate
i) the hydrolysis constant,
ii) degree of hydrolysis and
iii) pH of 0.1M CH3COONa solution (pKa for CH3COOH is 4.74).

42. An organic compound (A) of molecular formula C3HsO gives turbidity within 5-10 min on reaction with anhydrous ZnCI/HCI.Compound (A) on treatment with sodium hypochlorite gives a carbonyl compound (B) which on further chlorination gives compound (C) of molecular formula C3H3OCI3
Identify (A)(B) and (C). Explain the reactions

43. Styrene polymerises to polystyrene when heated in the presence of peroxide initiator.
(i) what is the mechanism involved?
(ii) Give the initiation step for the above process.
(iii) How does the chain propogate in the above mechanism?
(iv) How is the above chain reaction terminated?