CBSE XII CHEMISTRY QUESTION PAPER

CBSE XII CHEMISTRY QUESTION PAPER

1. Series SMA asi. 56/1

Code No.
Ai endl ae a me ginn 5 HTS
Roll No. Rare fered |

Candidates must write the Code on
the title page of the answer-book.

+ wash Re RG Age Be!

0 ma ao ees ait Ree de ae a AAA A o a fe

oo ga sa ea we À 30 ma À

6 goo a amt fram Ye A, a aie ara fa |

owe a Tr fer 15 fine ar are feo man À om a rr alg à
10.15 3 fem ET ı 10.15 98 À 10.30 28 7 um daa on À EN te
wa ore 5 dam & omega we aE are at Fe

+ Please check that this question paper contains 12 printed pages.

+ 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 am, the

students will read the question paper only and will not write any answer
‘on the answer-book during this period.

waren fers (ares)

CHEMISTRY (Theory)

Prefer za : 3 mè AAA Sie : 70

Time allowed : 3 hours Maximum Marks : 70

56/1 1 P.T.O.

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(ui) weston 28 à 30 dé-sae wer À | nr en à fore 5 sis à 1

(vii) ae an spi at
1

General Instructions :

15,

2.

3.

56/1

@ All questions are compulsory.
(ii) Marks for each question are indicated against it.

(ii) Questions number 1 to 8 are very shortanswer questions and
carry 1 mark each.

(iv) Questions number 9 to 18 are short-answer questions and carry
2 marks each.

(0) Questions number 19 to 27 are also short-answer questions and
carry 3 marks each.

(wi) Questions number 28 to 30 are long-answer questions and carry
5 marks each.

(vii) Use Log Tables, if necessary. Use of calculators is not allowed.

feet sie sofas a $8 age A
How may the conductivity of an intrinsic semiconductor be increased ?

ae a at eo A ı
Define ‘peptization’. A

fre doh owt da froin $8 fa om À ?
How is copper extracted from a low grade ore of it ?

3. 4 SbH, oft Bi, # aby fus mue arras à, ote wh? 1
Which is a stronger reducing agent, SbH, or BiH,, and why ?

5 34 CH, =CH-CH,-C=CH RARA AA dam ame? 1
What happens when bromine attacks CH, = CH - CH, - C = CH?

6. frafefaa a1 amé. (IUPAC) am fahre : 1

o
u
CH, - CH, - CH = CH-C-H

Write the IUPAC name of the following :

o
1
CH, - CH, - CH = CH-C-H

7. RRA deer fete toga Hanes ora A

mati 1
Write the structure of the product obtained when glucose is oxidised with
nitric acid.

8. tempeh ote ore wat à ata sia A ı 1

Differentiate between disinfectants and antiseptics.

9. da Rene, aH foe a ofa sk a at area à ate A da
me aif | fret fern at tee arse seat area fm mom dae? 2

sam
am AI 15 MA ai Mr IT 1389 8 cm? mo we ah
RO za freer ah crema fa A E

Express the relation among cell constant, resistance of the solution in
the cell and conductivity of the solution. How is molar conductivity of
a solution related to its conductivity ?

oR

The molar conductivity of a 1:5 M solution of an electrolyte is found
to be 138-9 S cm? mol”. Calculate the conductivity of this solution.

56/1 3 P.T.O.

4. 10. A à dev à feces se at À 1 ae se afters at sina
@ opt RS ae Gi) ond HS aw, Te SR AA
A reaction is of second order with respect to a reactant. How is its rate
affected if the concentration of the reactant is (i) doubled (ii) reduced to
half?

11. fas mat A a A à fore ete At eme wy à am à
ao
@ fa
Gi) fen
ñas a8 fier fart a sete A

Which methods are usually employed for purifying the following
metals

@ Nickel
Gi) Germanium

Mention the principle behind each one of them.

12. frafefen dd à fon sage arm AR ee saat uate A :
@ NF, we Sm dite à safe NCI, ter met à 1
(i) SEA ore anges tn
Explain the following facts giving appropriate reason in each case :
(@ NF is an exothermic compound whereas NCI is not.
(ii) All the bonds in SF, are not equivalent.
13. ff carafe a weet AA
@ nor +T+H—
Gi) MnOj + NO + Ht —
Complete the following chemical reaction equations :
@ 07 +17 + Ht —

Gi) MnOÿ + Noy + H* —

56/1 4

5. 14. tee à ore sata series A a at AA A
fee 1
Explain the mechanism of acid catalysed hydration of an alkene to form
corresponding alcohol.

15. freie A fee:
E E at sitet tele aa à ar

genta at à 1

Gi) RR aaa a anette dar à 1
Explain the following behaviours : a

(Alcohols are more soluble in water than the hydrocarbons of
comparable molecular masses.

(ii) Ortho-nitrophenol is more acidic than ortho-methoxyphenol.
16. wae & fee ana Tames we A ff a ate fae:
De a

ai) a are

Deseribe the following giving the relevant chemical equation in each
case :

6) Carbylamine reaction

Gi) Hofmann's bromamide reaction

17. Profiter aa aa at q A :
@ CgH¿NCl + H¿PO, + H,O —>
Gi) C¿H¿NH, + Br (aq) —>
Complete the following reaction equations
(1) OgH¿NCl + H¿PO, + H,O —>
Gi) CgH¿NH, + Br (aq) —>
18. Ta AAA A

What are food preservatives ? Name two such substances.

56/1 5 P.T.O.

6. 19, ae wae Bae waa aire Set e der À 1 ale ar wem at fer
1278 pm &, At ate arg an warn vate fe |
(Cu 3 TA Kam = 63:55 u ah Re HON N, = 6.02 x 10% mot)
sa
ara a fre da wa aan a ad ge AAA 286-65 pm À 1
SEA 187 gem RL ER Yan a AAA dom a A
AT 1 (Fe a VO ARA = 560 u)
Copper erystallises with face centred cubic unit cell. If the radius of
copper atom is 127-8 pm, calculate the density of copper metal.
(Atomic mass of Cu = 6355 u and
Avogadro's number N, = 6:02 x 10% mol”)
oR
Iron has a body centred cubic unit cell with the cell dimension of
286-65 pm. Density of iron is 7:87 g cm”. Use this information to
calculate Avogadro's number. (Atomic mass of Fe = 56-0 u)

20. 1 cm =m ait 50 cm me a 0.05 M NaOH fram à sion am fg
fee 5-55 x 10° ohm À 1 Fae sere, sree ste shee area am oat
LR
The electrical resistance of a column of 0-05 M NaOH solution of

diameter 1 cm and length 50 cm is 5:55 x 10° ohm. Caleulate its
resistivity, conductivity and molar conductivity.

21. aa wh ea À seg an de sm à, at sem
N, (g) + 0, (g) = 2 NO (g)
arg sum weet À ı eae AT 1500 Km we feats K= 1.0 x 105 € 1
aa chf ate fm Où à wee me À NS] = 0-60 mol Lae
10,1 = 020 mol 1714 ı fr 1500 K a af a SHARE SK
da aT fn A 1

The reaction, Np(g) + Op(g) = 2NO(g) contributes to air pollution
whenever a fuel is burnt in air at a high temperature. ‘At 1500 K,
equilibrium constant K for it is 1-0 x 10% Suppose in a case
IN?) = 0:80 mol L'! and [0,] = 0:20 mol L'! before any reaction
‘occurs. Calculate the equilibrium concentrations of the reactants and
the product after the mixture has been heated to 1500 K.

56/1 6

7. 22. wae à fee UH A Sa A au, Pf veh at caren AA :

56/1

@
Gi)

ii)

taf (Aerosol)
SEA (Emulsion)
fr (Micelle)

Explain the following terms giving a suitable example for each :

0)
Gi

Aerosol
Emulsion

Micelle

@

Gi)

ii)

AR À Lo CID ate aS ER wg Shah eet set
da, 42 oe 4 A EI

Byers
doh ter armen feos ach ste set ag à à

Yam apt Ft gta 6a) Sot as frond ae aft À où fe
Brit an Feet a

am a à fc saree (0-34 V) À 1 da ae a

How would you account for the following :

@

Gi)

Among lanthanoids, Ln (III) compounds are predominant.
However, occasionally in solutions or in solid compounds, +2 and
+4 ions are also obtained.

The Eyes

metal in the first series of transition elements showing this
behaviour.

for copper is positive (0:34 V). Copper is the only

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

7 P.T.O.

8. 24.

26.

27.

56/1

Footer soie oem (A) & am sh a A à
Hé A:
@ (Co(en); Cly]* (en = r-1,2-2r rm)
(ii) [Cr(C209)
Git) [Co(NHz)y Clg]
(Gem Anís Cr = 24, Co = 27)
Name the following coordination entities and draw the structures of their
stereoisomers :
) [Co(en) Clgl* (en = ethan-1,2-diamine)
Gi (Cr(C209)
(iii) [Co(NH¿)g Clg]
(Atomic numbers Cr = 24, Co = 27)
fan set à am a
Mia A fated (chirality) a Farad À 2 we see A
Gi) Free Af à à seer KOH ae safes A ear
@ sk ai ?
CH,CHCICH,CH, 3% CH;CH,CH,CI
Gi) GH ah sy ar a afte ast à ser à otk wi ?
CI
LW [NV
Answer the following questions
) What is meant by chirality of a compound ? Give an example.
(ii) Which one of the following compounds is more easily hydrolyzed
by KOH and why ?
CH¿CHCICH¿CHz or CH¿CH¿CH¿Cl
(i) Which one undergoes Sy2 substitution reaction faster and why ?
PARE oes DOLE
orga ait pr À Frère en sie À 2 gate at oaths dear à er
aid?
What is essentially the difference between a-glucose and f-glucose ? What
is meant by pyranose structure of glucose ? .
aña ER ageet & de sin we ART |S A un
ae A 1
Differentiate between thermoplastic and thermosetting polymers. Give
‘one example of each.

9. 56/1

(a)

(b)

@

©

(a)

(0)

(a)

(b)

Fate vat e AA :
G) iAH (Mole Fraction)
a) a er

Ww arme one wed 150 mm RE 460 g à ge oT
1 mar Prem -034°0 ve Mage Dem #1 werd am Men Kamm am

À 2 (am à far K,= 1:86 K kg mol)

aaa
frafefen a ee aan:
De de à ge à dae Fd a Prem
GO Uw free & fore as sar fie

23

a 500 g À go freer a gara, fer (CHO) Fw Pera
a fra an ares 10042°C 8 1 70 A

à fade ait fi aor qa mé à ?
(wa + fer K, = 0-512 K kg mol)

Define the following terms
® Mole fraction

ii) Ideal solution

2,3

15:0 g of an unknown molecular material is dissolved in 450 g of
water. The resulting solution freezes at —0:34*C, What is the

molar mass of the material ? (K; for water = 1-86 K kg mol!)
OR

Explain the following :

() Henrys law about dissolution of a gas in a liquid

(ii) Boiling point elevation constant for a solvent

A solution of glycerol (C¿H¿Oy) in water was prepared by
dissolving some glycerol in 500 g of water. This solution has a
boiling point of 100-42°C. What mass of glycerol was dissolved to

make this solution ? (K;, for water = 0-512 K kg mol”)

P.T.O.

10. 29.

ser

(a)

5)

(a)

(0)

(a)

)

fa fit af devant are A

@
Gi)

N05,
XeOF,

Aaa set A ren A

@

(0)

Free areas a a qui af

@
a)

Fate sr 28 an aie :
angina ster siete à dacs AA
cio we de À vats vom da à 1

@
i)
Gi)

Draw the molecular structures of the following compounds :

@
Gi)

Explain the following observations :
Sulphur has a greater tendency for catenation than oxygen.

@
a)
Gi)

feia a a wea UT (catenation) a wart sem Art

ta

LA ater ICI fe Bean à 1

Gs at a wich sem A A
ater e, fax oh (E) Marge (CL) à AA

A à

aaa

Cu + HNO, (D —

XeF, + OF, —

m?

N¿Os
XeOF,

ICI is more reactive than Ip.

Despite lower value of its electron gain enthalpy with
negative sign, fluorine (F,) is a stronger ‘oxidising agent

than CL.

oR

10

2,3

2,3

11. 80.

56/1

(a)

(b)

(a)

(0)

(a)

(0)

Complete the following chemical equations :

@
Gi)

Cu + HINO, (dilute) —
XeF, + 0,F, —

Explain the following observations :

(0)

Gi)

Gi)

Phosphorus has greater tendency for catenation than

nitrogen.
Oxygen is a gas but sulphur a solid.
‘The halogens are coloured. Why ?

33 Tate en a free Pan ate a qui A :

0)
Gi)

a à agate aa à
A a ser à

ts fre, fr aa 47 CÇH,,0 À, 2,4-DNP A mar
2, da as a a ae à, at O at A ac à 1
via aachen 1 ae As sre ter à | aie at weet

a

a

fra & ata sit ar à fern cares sf at den

@
a)

er ak th À
ol

23

a fr a oe amd Ral SA

Lu
@

Gi

Gi)

Petr, den, Mariara wem (HON à ft

aria)

Fa a, 34 a, RA are
(ma aa)

CH,CH,CH (Br) COOH, CH,CH (Br) CH¿COOH,
(CH,),CH COOH (I arr!)

1”

2,3

P.T.O.

12. (a)

(b)

(a)

(b)

Write a suitable chemical equation to complete each of the
following transformations :

(0) Butan-1-ol to butanoic acid

(Gi) 4-Methylacetophenone to benzene-1,4-dicarboxylic acid

An organic compound with molecular formula CgH, 90 forms
2,4-DNP derivative, reduces Tollen’s reagent and undergoes

Cannizzaro's reaction. On vigorous oxidation it gives
1,2-benzenedicarboxylic acid. Identify the compound.

OR

Give chemical tests to distinguish between

(G) Propanol and propanone

(ii) Benzaldehyde and acetophenone

Arrange the following compounds in an increasing order of their

property as indicated :

@ Acetaldehyde, Acetone, Methyl tert-butyl ketone (reactivity
towards HCN)

(ii) Benzoic acid, 3,4-Dinitrobenzoic acid, 4-Methoxybenzoic
acid (acid strength)

(iii) CH¿CH,CH (Br) COOH, CH¿CH (Br) CH,COOH,
(CH,),CH COOH (acid strength)