CCE RR
—
560 003
KARNATAKA SECONDARY EDUCATION EXAMINATION BOARD, MALLESWARAM,
BANGALORE – 560 003
— 2016
S. S. L. C. EXAMINATION, JUNE, 2016
MODEL ANSWERS
83-E (Chem.)
CODE NO. : 83-E (Chem.)
:
: 22. 06. 2016 ]
Date :
22. 06. 2016 ]
Subject : SCIENCE
(
/ Chemistry )
(
/ New Syllabus )
(
/ Regular Repeater )
(
/ English Version )
[
: 80
[ Max. Marks : 80
Qn.
Nos.
Value Points
1.
The substance used as flux during the extraction of iron by the
Total
Haematite ore is
Ans. : (B) — limestone
4.
1
A part of s-block in the modern periodic table is given here. The correct
arrangement of these atoms in the increasing order of their atomic size is
Ans. : (C) — Mg, Na, K
1
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83-E (Chem.)
2
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Qn.
Nos.
Value Points
9.
A person is trying to electroplate a brass article with silver. Even after
Total
passing electric current through the electrolyte, he finds that silver has
not been deposited. Identify the mistake here.
1
Ans. : (D) — He has used silver as cathode.
14.
What is saponification ?
Ans. :
Process of neutralizing the fatty acids present in the oils or fats by
adding sodium hydroxide or potassium hydroxide.
16.
1
Write the structural formula of salicylic acid.
Ans. :
1
19.
What is ionisation energy ? How does ionisation energy vary along the
period in modern periodic table ?
OR
What are electropositive atoms ? How does electropositivity vary along
the period in modern periodic table ?
Ans. :
The energy required to remove the electron from the outermost shell of
an atom.
1
Increases
1
2
OR
Atoms which give up electrons are called electropositive.
1
Decreases
1
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83-E (Chem.)
Qn.
Nos.
Value Points
24.
Write any two differences between crystalline silicon and amorphous
Total
silicon.
Ans. :
Crystalline Silicon
Amorphous Silicon
(i)
It is a dark grey crystalline solid
(i)
It is a brown powder
(ii)
Slightly conducts electricity
(ii) Does not conduct electricity at
low temperature
(iii)
Comparatively it is less reactive
(iii) Comparatively it is more reactive
(iv)
It does not burn in the air even
(iv) When heated in air, it oxidises at
when heated
the surface level and catches fire
( Any two pairs of differences )
25.
1+1
2
Explain first two stages of manufacturing paper.
OR
Write one special property of the following glasses and mention one use of
each :
(a) Borosilicate glass
(b)
Sodalime glass.
Ans. :
First two stages of paper manufacturing :
i)
Pulping

ii)
1
2
Wood is chipped and made into fibre
Mixing additives :

Fillers like chalk or china clay are added.
1
2

Pulp is fed to paper machine to form paper web.
1
2

Water is removed by pressing and drying.
1
2
2
OR
(a)
Hard glass / withstands temperature fluctuations. ( Any one )
1
2
Uses : Laboratory apparatus / preparation of pipelines.
( Any one )
(b)
1
2
Melts ( fuses ) easily.
Uses :
1
2
Window glasses / electric bulb / plate glass / bottles /
jars / building blocks, cheaper tablewares.
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( Any one )
1
2
2
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83-E (Chem.)
Qn.
Nos.
30.
4
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Value Points
Total
Draw the diagram of the apparatus used in electrolysis.
Ans. :
2
32.
In test tubes A and B, zinc sulphate solution and silver nitrate solution
are taken respectively. Copper turnings are added to both test tubes. In
which of the two test tubes do you observe the reaction ? Justify your
answer with scientific reason.
Ans. :
Test tube B containing silver nitrate solution.
1
Because copper being more reactive than silver, displaces silver from
silver nitrate solution.
34.
1
2
A balloon filled with helium gas is kept inside the refrigerator. What
change do you observe in the size of the balloon after some time ? State
the law that justifies your answer.
Ans. :
Size of the balloon decreases.
1
At constant pressure, the volume of a fixed mass of a gas is directly
proportional to its absolute temperature.
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1
2
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5
83-E (Chem.)
Qn.
Nos.
Value Points
35.
Explain the process of manufacturing common sugar from sugarcane
Total
juice.
OR
Explain the process of manufacturing ethyl alcohol using molasses. Name
the enzymes involved in this process.
Ans. :
Steps after extracting sugarcane juice.
1
2

Juice is warmed and run into settling tank.

Decanted juice is made alkaline with calcium hydroxide and
1
2
steamed to coagulate protein.

Clear juice is concentrated into a syrup by evaporation under
reduced pressure.
1
2

Syrup is cooled to crystallise.
1
2

Crystals are dissolved in hot water and decolourised using animal
charcoal or norite and filtered.

1
2
Filtrate is concentrated by evaporation under reduced pressure and
crystallised to get white crystals of sugar.
1
2
3
OR
Manufacturing of ethyl alcohol.

Molasses is diluted with water and acidified by adding dilute
sulphuric acid.
1
2

Yeast is added to the solution.
1
2

Temperature is maintained at around 308 K.
1
2

Fermented matter ‘wort’ is fractionally distilled to get ethyl alcohol.
1
2
Invertase
1
2
Zymase.
1
2
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83-E (Chem.)
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Qn.
Nos.
Value Points
38.
Draw the diagram of blast furnace used in the extraction of iron and label
Total
the following parts :
(a)
Waste gases
(b)
Molten iron.
Ans. :
Blast Furnace
Waste gases
Molten iron
For diagram
For labelling parts
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1
2
+
1
2
3
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Qn.
Nos.
41.
83-E (Chem.)
Value Points
(a)
Total
The boxes given here with numbers 1, 2, 3 and 4 represent a class of
hydrocarbons. Write the name of first member of that respective
class according to the numbers given.
(b)
Name
the
functional
group
in
the
following
structures
of
hydrocarbon compounds and name these hydrocarbon compounds :
(i)
(ii)
Ans. :
a)
b)
(1)
Methane
1
2
(2)
Ethyne
1
2
(3)
Cyclopropane
1
2
(4)
Benzene.
1
2
(i)
Carboxyl group
1
2
Butanoic acid
1
2
Aldehyde
1
2
Propanaldehyde / Propanal.
1
2
(ii)
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