#### 12th Standard English Medium Chemistry Reduced Syllabus Public Exam Model Question Paper with Answer key - 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. 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

2. The repeating unit in silicone is v

(a)

SiO2

(b)

(c)

(d)

3. The ionisation energy of Ga is higher than that of Al because of_________

(a)

more effective nuclear charge of Ga

(b)

smaller atomic size of Ga

(c)

larger size ofGa

(d)

both (a) and (b)

4. The magnetic moment of Mn2+ ion is

(a)

5.92BM

(b)

2.80BM

(c)

8.95BM

(d)

3.90BM

5. IUPAC name of the complex K3[Al(C2O4)3] is

(a)

potassiumtrioxalatoaluminium(III)

(b)

tassiumtrioxalatoaluminate(II)

(c)

potassiumtrisoxalatoaluminate(III)

(d)

potassiumtrioxalatoaluminate(III)

6. Iodine crystals are __________.

(a)

covalent

(b)

ionic

(c)

metallic

(d)

molecular

7. The addition of a catalyst during a chemical reaction alters which of the following quantities? (NEET)

(a)

Enthalpy

(b)

Activation energy

(c)

Entropy

(d)

Internal energy

8. MY and NY3, are insoluble salts and have the same Ksp values of 6.2 ×10-13 at room temperature. Which statement would be true with regard to MY and NY3?

(a)

The salts MY and NY3 are more soluble in 0.5M KY than in pure water

(b)

The addition of the salt of KY to the suspension of MY and NY3 will have no effect on their solubility’s

(c)

The molar solubilities of MY and NY3 in water are identical

(d)

The molar solubility of MY in water is less than that of NY3

9. An aqueous solution with pH value zero is

(a)

acidic

(b)

basic

(c)

amphoteric

(d)

neutral

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. If x is the amount of adsorb ate and m is the amount of adsorbent, which of the following relations is not related to adsorption process?

(a)

x/m=f(P) at constant T

(b)

x/m=f(T) at constant P

(c)

P = f(T) at constant x/m

(d)

x/m = PT

12. The common name for 4-hydroxy toluene is ________

(a)

p-cresol

(b)

m-cresol

(c)

resoricinol

(d)

catechol

13. Assertion: p – N, N – dimethyl amino benzaldehyde undergoes benzoin condensation
Reason: The aldehydic (-CHO) group is meta directing.
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

14. Electrolytic reduction of nitrobenzene in strongly acidic medium gives

(a)

aniline

(b)

p - aminophenol

(c)

m-nitroaniline

(d)

azoxybenzene

15. Denaturation does not involve

(a)

breaking up ofH-bonding in proteins

(b)

the loss of biological action of enzyme

(c)

the loss of secondary structure

(d)

loss of primary structure of proteins

16. Part II

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

6 x 2 = 12
17. What is leaching?

18. Give the structure of CO and CO2.

19. How would you account for the following? The electron gain enthalpy with negative sign is less for oxygen than that of sulphur.

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

21. Give any three characteristics of ionic crystals.

22. For the reaction
Cl2 (g) + 2NO (g) ⟶ 2NOCI(g)
The rate law is expressed as
rate = K[Cl2] [NO]2
What is the overall order of this reaction

23. A lab assistant prepared a solution by adding a calculated quantity of HCl gas 250C o to get a solution with [H3O+]= 4$\times$10-5M. Is the solution neutral (or) acidic (or) basic.

24. Define conductance. Give its unit

25. Draw the major product formed when 1-ethoxyprop-1-ene is heated with one equivalent of HI

26. Part III

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

6 x 3 = 18
27. What is vapour phase method?

28. Give reason for the following:
(i) Compounds of transition elements are generally coloured,
(ii) MnO is basic while Mn2O7 is acidic.
(iii) Calculate the magnetic moment of a divalent ion in aqueous medium if its atomic number is 26.

29. Show that SHE can act both as a anode as well as cathode.

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

31. What are the oxidation products of glycerol?

32. How will you convert benzaldehyde into the following compounds?
(i) benzophenone
(ii) benzoic acid
(iii) $\alpha$ - hydroxyphenylaceticacid.

33. Write a note on acidic nature of nitro alkanes.

34. Write the monomers of the following sugars and explain how they are linked.
(i) Sucrose
(ii) Maltose
(iii) Lactose

35. Give the structure of melamine formaldehyde resin.

36. Part IV

5 x 5 = 25
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 structure of inter halogen compounds

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

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

1. An element with molar mass 2.7 x 10-2 kg mol forms a cubic unit cell with edge length 405 pm. If its density is 2.7 x 103 kg m-3, What is the nature of the cubic unit cell?

2. The time for half change in a first order decomposition of a substance A is 60 seconds. Calculate the rate constant. How much of A will be left after 180 seconds?

1. What is the pH of an aqueous solution obtained by mixing 6 gram of acetic acid and 8.2 gram of sodium acetate and making the volume equal to 500 ml. (Given: Ka for acetic acid is  $1.8\times10^{-5}$)

2. Write the characteristics of catalysts.

1. An organic compound (A) molecular formula CH2O reacts with CH3MgI to give compound (B). Compound (B) liberates Hydrogen with metallic sodium. Compound (B) in the presence of Con. H2SO4 at 410 K on dehydration to give compound (C) molecular formula C4H10O. Identify (A), (B) and (C). Explain the above reactions.

2. How does NHreact with the following?
(i) HCHO
(ii) CH3CHO
(iii) C6HSCHO
(iv) CH3 COCH3