Cbse 2009 Chemistry Board Paper Class Xii

I

Series SSO

(5)s

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Candidates must write the Code on

Roll No. W1

56/3

Code N~.

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the title page of the answer-book.

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Please check that this question paper contains 12 printed pages.

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Code number given on the right hand side of the question paper should be written on the title page of the answer-book by the candidate.

•

Please check that this question paper contains 30 questions.

•

Please write down the Serial Number of the question before attempting it.

•

15 minutes time has been allotted to read this question paper. The question paper will be distributed at 10.15 a.m. From 10.15 a.m. to 10.30 a.m., the student will read the question paper only and will not write any answer on the answer script during this period.

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CHEMISTRY

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56/3

Maximum

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Marks:

70

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General Instructions : (i)

All questions are compulsory.

(ii)

Marks for each question are indicated against it.

(iii)

Questions number 1 to 8 are very short-answer questions and mark each. carry Questions number 9 to 18 are short-answer questions and carry 2 marks each.

(iv)

1

(v)

Questions number 19 to 27 are also short-answer carry 3 marks each.

(vi)

Questions number 28 to 30 5 marks each.

(vii)

Use Log Tables, if necessary. Use of calculators

are long-answer

questions

and

questions and carry is not allowed.

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1.

What is the number of atoms in a unit cell of a face-centred cubic crystal? fcnm ~-~

2.

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What is the 'coagulation' process? (coagulation)"5ffii11 CFIT mm ~ i~'

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if ~

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Why is red phosphorus less reactive than white phosphorus? ~ ~1~~*1 cnl ~ ~ ~1~~*1 cpr rs:h'1I~I1<.1 cp:ff mm ~ ?

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6) 56/3

1 What is meant by the term 'pyrometallurgy' ? inN_~'

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CFIT ~

mm ~?

2

I 5.

Write the structural 1-~H(.14~
6.

1

formula of I-phenylpentan-l-one.

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1

Give the IUPAC name of the following compound: H2C = CH - CH - CH2 - CH2 - CH3 1

OH r ... r .r. .. ~

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H2C = CH - CH - CH2 - CH2 - CH3 ·1

OH /, i7~) ',-

What does '6,6' indicate ~-6,6

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1

in the name nylon-6,6 ? 'Cp1T

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2 Complete the following chemical reaction equations (i) XeF2 + H20 --7 (ii) r

10.

56/3

BH3 + HgC12 --7 r r.

r

~

~J-;lcp\u~

(i)

XeF 2 + H20

(iD

PH3 + HgC12 --7

ciT ~

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--7

Complete the following reaction equations (i)

:

0(CH3 0

:

2

+ HI --7

3

p.T.a.

~-----

------------

.

Which one in the following pairs undergoes SN1 substitution faster and why ?

11.

CI

(i)

/I~

(ii)

~

2

rn

or

~

Cl.

r r r: ~

reaction

if

Cl

or~

it ~

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it ~

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(i)

/I~ Cl

(ii)

~

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3l~

2

~comPlete ,

the following chemical reaction equations:

(i)

MnO~ (aq) + C2O~- (aq) + H+ (aq) ~

(ii)

Cr2O~- (aq) + Fe2+ (aq) + H+ (aq) -7

r r r

r:m~

~~·iICPo(Y~

cit 1:[Uf

.

~

(i)

MnO~ (aq) + C20~- (aq) + H+ (aq) ~

(ii)

Cr20~- (aq) + Fe2+ (aq) + H+ (aq) -7

2

Describe the Tole of the following : /' /- I

13. _

..

-,""

~

NaCN in the extraction of silver from a silver ore. (ii)

Cryolite in the extraction of aluminium from pure alumina.

r rr

56/3

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(i)

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(ii)

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14.

2

Define the following: (i)

Order of a reaction

(ii) ,Activation energy of a reaction r

15.

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31f~

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(ii)

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What type of cell is a lead storage battery ? Write the anode and the cathode reactions and the overall cell reaction occurring in the use of a lead storage battery.

2

OR

Two half cell reactions of an electrochemical cell are given below : MnO~ (aq) + 8 H+ (aq) + 5 e-

-7

Sn2+ (aq) -7 Sn4+ (aq) + 2 e-,

Mn2+ (aq) + 4 H20 (l), EO =

EO

= + 1·51 V

+ 0·15 V

Construct the redox equation from the two half cell reactions and predict if this reaction favours formation of reactants or product shown in the equation. mm 31R

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MnO~ (aq) + 8 H+ (aq) + 5 e-

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Sn2+ ,(aq) -7 Sn 4+ (aq) + 2 e-, ~ ~

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Mn2+ (aq) + 4 H20 (l), EO

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= + 0·15 V

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16. Name the four bases present in DNA. Which one of these is not present in RNA ? 'qR ~ ~ ~ ~ ~ DNA if fc1'C.l~I..-j ~ I ~ it ~ ~ RNA if ~ ~

56/3

2

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5

p.T.a.

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(.!_71 Differentiate between condensation and addition polymerisations.

Give

one example each of the resulting polymers. ~

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?!g~ Name two fat soluble vitamins, their sources and the diseases caused '-- -

due to their deficiency in diet. qm if :!c.1•.p{ (1 G) fcR:1f~ it -;w:r,

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Silver crystallises with face-centred cubic unit cells. Each side of the unit cell has a length of 409 pm. What is the radius of an atom of silver ? (Assume that each face atom is touching the four corner atoms.) ~ ~-~ er.:fm ~ iwr if r9h~r(1c1 ~ ~ I ~ iwr it ~ fcfnR cnl ~409pm~ I ~~cnl~CFIT~? (~~~fcn~ "Cf)\ill ~ I) ') ~:qRf ~ it ~3TI ~

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20.

A first order reaction has a rate constant of 0·0051 min-I. If we begin with 0·10 M concentration of the reactant, what concentration of the reactant will be left after 3 hours ? ~

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A voltaic cell is set up at 25° C with the following half-cells: All A13+ (0·0010 M) and Ni I Ni2+ (0·50 M). Write the equation for the cell reaction that occurs when the cell generates an electric current and determine the cell potential. (Given: EO Ni 2 +/ Ni = - 0·25 V,

EO AI 3 + / Al = - 1·66 V)

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22. What happens in the following activities and why? (i)

An electrolyte

(ii)

A beam of light is passed through a colloidal solution.

(iii)

An electric current

r..or or.,

,

M3TI if

is added to a hydrated

CF1T

ferric oxide sol in water.

is passed through a colloidal solution.

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3

Explain the following : (i) Low spin octahedral

complexes of nickel are not known.

(ii)

The n-complexes are known for transition

(iii)

CO is a stronger

elements

only.

ligand than NH3 for many metals.

OR Compare the following complexes with respect to structural shapes of units, magnetic behaviour and hybrid orbitals involved in units : (i)

[Ni(CN)4J2-

(ii)

[NiC14J2-

(iii)

[CoF 6J3-

[At. Nos. : Ni = 28;

r rr

Co = 27J-1-

(i)

~

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(ii)

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(iii)

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f:ikff~f.(9<1 ~ (cnT~cffil) ~ ~ ~cnl~~'if ~ (i)

[Ni(CN)4J2-

(ii)

[NiC14J2-

(iii)

[CoF 6J3-

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56/3

L1

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Ni = 28; Co = 27J

7

p.T.a.

------,---.-------------

I

24.

(i)

Many of the transition good catalysts.

(ii)

The metallic radii of the third (5d) series of transition elements are virtually the same as those of the corresponding members of the second series.

(iii)

There is a greater range of oxidation states than among the lanthanoids.

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(ii)

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56/3

~

and their compounds

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(i)

The boiling point methoxymethane.

ethanol

(ii)

Phenol is more acidic than ethanol.

(iii)

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(iii)

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higher

than

that

of

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Complete the following reaction

°

(i)

II R - C - NH2

(ii)

C6HsN2Cl

(iii)

C6HsNH2 + Br2 (aq) --7

-B ~

°) + H20 --7

8

~

~

I 31f~

equations

LiAlH4 H2

+ H3P02

~

are more acidic than phenol.

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I1m1 ~

:

(i)

among the actinoids

ctt mm ~ I

Explain the following observations

and p-nitrophenols

can act as

:

iT -::$l(-q
Q~rfl~-51

r r r. . a:tqc..iich ..i'i

26.

elements

~

it ~ ~ ~ d~~4r 25.

3

How would you account for the following:

~

:

~

~

3

• r rr

~

°

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(i)

R - C - NH2

(ii)

C6HSN2Cl + H3P02

(iii)

C6HSNH2 + Br2 (aq) ~

)

H20

+ H20 ~

What are the following substances? them. (i) (ii) (iii) r

28.

Tf ~ i: ~

LiAlH4 .

II

27.

it

Give one example of each of 3

Cationic detergents Enzymes Sweetening agents

rr~.\:

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cp:rr

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(i)

~

(ii)

l!,~I~.,

(iii)

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(a)

Define the foll{)wingterms: (i) Mole fraction (ii) Van't Hoff factor

(b)

100 mg of a protein is dissolved in enough water to make 10·0 mL of a solution. If this 'solution has an osmotic pressure of 13·3 mm Hg at 25° C, what is the molar mass of protein ? (R = ,0·0821 Latm mol-1 K-1 and 760 mm Hg = 1 atm.)

31\.j"I~ctl

(r"dl~ctll-t)

•

(~)

5

OR

(a)

(b)

56/3

What is meant by : (i)

Colligative properties

(ii)

Molality of a solution

What concentration of nitrogen should be present in a glass of water at room temperature? Assume a temperature of 25° C, a total pressure of 1 atmosphere and mole fraction of nitrogen in air of 0·78. [KH for nitrogen = 8·42 x 10-7 M/mm Hg] 9

5

P.T.D.

(a)

(b)

Hkjrc1r~d ~

~ ~

l1Wr

(ii)

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~

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~

100 mg 1WIT ~ ~ 25° C 1R ~ fcK;r:R CflT

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(i)

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if ~

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10·0 mL fcK;r:R ~ 13·3 mm Hg m, "ffi mif.:r

CflT

?

~

(R = 0·0821 L atm mol-1 K-1

31R

760 mm Hg = 1 atm.)

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(a)

(b)

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(ii)

fcK;r:R cn1

~

~ ~

~

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(b)

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~

~

25° C ~ 31R ~

am 0·78 ~

I

if ~

f1rc;mr

~

~

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rjl~~I\!jrj

1 QCl1lr~~o(. KH

t

CflT ~

Cf
31R ~

~

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if ..~,) ..

= 8·42 x 10-'-:7M/mm Hg]

Write chemical equations to illustrate the following name bearing reactions: (i) Cannizzaro's reaction (ii) Hell-Volhard -Zelinsky reaction Give chemical tests to distinguish between the following pairs of compounds: (i) Prop anal and Propanone (ii) Acetophenone and Benzophenone (iii) Phenol and Benzoic acid

5

OR (a)

How will you bring about the following conversions : (i) Ethanol to 3-hydroxybutanal (ii) Benzaldehyde to Benzophenone

(b)

An organic compound A has the molecular formula CSH1602' It gets hydrolysed with dilute sulphuric acid and gives a carboxylic acid B and an alcohol C. Oxidation of C with chromic acid also produced B. C on dehydration reaction gives but-l-ene. equations for the reactions involved.

56/3

10

Write 5

~~1- I

(a)

(b)

rrjkjrc1~d

~

(i)

~H~I~ ctt

(ii)

~-~-~rC1«h1

rrjkjrc1r~d

cit

~3TI

~

W~ ~

'('1<:iI~HCP W-llcp'('UI

:

~

~

# f~

~

cn1 ~

~

~

ft;m: ~-~

'('1<:iI~Hcp ~

~: (i)

~

(ii)

Q<:ilcllhlrjlrj

~

(iii)

~

~~sCP

#

>WAR

31R

~

#

~o;J1llhlrjlrj

#

~

3l~ (a)

(b)

rrjkjrc1r~d

~yid'('UI

(i)

~

(ii)

~~rc:-s()ls-s

~

~-3-il.j~r2.d

C

cit

~:m

I

cit

1l'<1T

(a)

(b)

:

~o;J11lhl·.flrj

#

~

'R

~

?""~

#

(31TfUq-q:;

C ~ ~

<:il-\lcp'('UI CfiT I\'II~~

30.

~

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~

CfiT H~c1lcp'('ul

"

~

men A

~

r

~

cit

CSH1602)

~

B ~

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~

~

~ ~

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>rT({f

dY-q~rj

mm ~

C11

-B 'lft

I <:ir?\fQd

<:iC'.~Cp

~ B

~

-B

Qc:cnIQlc1

C

>rT({f mcrr ~

3WmT3TI

~

I

fc;m:

I

Draw the structures of the following : (i)

XeF4

(ii)

H2S207

Explain the following observations: (i)

Phosphorus nitrogen.

has a greater tendency for catenation

than

(ii)

The negative value of electron gain enthalpy is less for fluorine than that for chlorine.

(iii)

Hydrogen fluoride has a much higher boiling point than hydrogen chloride.

5

OR 56/3

11 .

P.T.D.

~~-~1~--------~~-~------~---------------------J1 (a)

(b)

(a)

(b)

Draw the structures of the following : (i)

PCIs (s)

(ii)

802-3

Explain the following observations: (i)

Ammonia has a higher boiling point than phosphine.

(ii)

Helium does not form any chemical compound.

(iii)

Bi (V) is a stronger oxidising agent than 8b (V).

H~r\1r~~

cfiT

~,,:qrll~ ~

(i)

XeF4

(ii)

H28207

H~r~r~~

3-fC/ctlChrllc€r

(i)

rll~~I'Jjrl

c€r

(ii)

~~~Irl

~

(iii)

~

:

cx:m§'1T ~

:

~I~~I"'~ if ~

~

~ I

QI~~I'Jjrl cK1l"'I~S c€r mm ~ I

~

c€r

~

31f'i::fCfi·Wffi

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cor

~cp11mm~

5

Qj~~I'Jjrl 1:Rj~

~. ~ q:q~

cor

I

~

~ ~

~ 31f'i::fCfi

31~ (a)

(b)

56/3

H~r\1r~~

c€r

~",-qrll~ ~

(i)

PCIs (s)

(ii)

80;-

H~r\1r~~

3-fC/\1IChrll ~

(i)

~1~lrl

(ii)

Qlr~~+i ~

(iii)

8b (V) c€r

c€r

~

~

:

31f'iW: ~ ~

~

~

q:q~

cor

"'1~I~HCh~

:

~

Bi (V) ~

~

31f'i::fCfi

12

~ ~ >I'if0

mm ~

I

I ~Y-qI~Ch

~

I

97,100