Karnataka SSLC Question Paper 2022 Answer Key Science Chemistry

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KARNATAKA SECONDARY EDUCATION EXAMINATION BOARD, MALLESHWARAM,
BANGALORE – 560 003
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S. S. L. C. EXAMINATION, MARCH/APRIL, 2022

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MODEL ANSWERS
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Date : 11. 04. 2022 ] CODE NO. : 83-E (Chem.)

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Subject : SCIENCE
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( ¡⁄—¤æ⁄fl´⁄À¤—⁄° / Chemistry )

( BMW«ŒÈ »⁄·¤®⁄¥¿»⁄fl / English Medium )

[ V⁄¬Œ⁄r @MO⁄V⁄◊⁄fl : 80
[ Max. Marks : 80

Qn.
Value Points Total

PART - B
( CHEMISTRY )

VII. Multiple Choice : 2×1=2

14. The gas liberated at the cathode in the electrolysis of water is

(A) Oxygen (B) Hydrogen

(C) Chlorine (D) Nitrogen.

(B) Hydrogen 1

RF/RR (A)-(200)-9046 (MA)-CHEM [ Turn over

83-E (Chem.) 2 CCE RF & RR
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15. Atomic number of chlorine is 17. The period number of this element in
modern periodic table is

(A) 2 (B) 7

(C) 4 (D) 3.

(D) 3 1

VIII. Answer the following questions : 4×1=4

16. State modern periodic law.

“Properties of elements are periodic functions of their atomic numbers.” 1

17. Write any two uses of Plaster of Paris.

Plaster of Paris is used in :

Supporting fractured bones

Making toys

Decorative materials
1 1
Making smooth surfaces. ( Any two ) +
2 2 1

18. Write the structural formula of ethene molecule.

1

CCE RF & RR 3 83-E (Chem.)

Qn.
Value Points Total

19. ZnO + C → Zn + CO

In this reaction name the reactant

i) that is oxidised and

ii) that is reduced.

1
Oxidised reactant is : C
2

1
Reduced reactant is : ZnO.
2 1

IX. Answer the following questions : 3×2=6

20. The pH values of A, B and C solutions are 5, 6 and 7 respectively. Which of

these solutions is more acidic in nature ? Why ?

Solution A is more acidic. 1

As it has more H + ions. 1 2

21. Draw the diagram to show the arrangement of the apparatus used for

testing the conductivity of salt solution and label ‘graphite rod’.

RF/RR (A)-(200)-9046 (MA)-CHEM [ Turn over

83-E (Chem.) 4 CCE RF & RR
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Testing the conductivity of a salt solution :

Graphite rod

Diagram — 1 1
2

Labelling — 1
2 2

22. Give reason :

a) Metals are used in making cooking vessels.

b) Sodium metal is stored in kerosene.

OR

Give reason :

a) When a calcium metal reacts with water, the liberated hydrogen gas

does not catch fire.

CCE RF & RR 5 83-E (Chem.)

Qn.
Value Points Total

b) Ionic compounds have high melting and boiling points.

a) Because, metals are good conductors of heat / having high melting

points / property of malleability. ( Any one ) 1

b) Sodium metal vigorously reacts with atmospheric oxygen and water, but

not with kerosene. 1 2

OR

a) The reaction of calcium with water is less violent. The heat evolved is

not sufficient for the hydrogen to catch fire. 1

b) Because a considerable amount of energy is required to break the

strong inter-ionic attraction. 1 2

X. Answer the following questions : 3×3=9

23. What is atomic size ? In the modern periodic table the atomic size decreases

along a ‘period’ and increases down the ‘group’. Why ? Explain.

The distance between the centre of the nucleus and the outermost shell

of an isolated atom. 1

In modern periodic table atomic size decreases along the period

because :

Electrons are being added to the outermost shell of an atom that tends

to pull the electrons closer to the nucleus / No new shells are added to

atom. 1

Atomic size increases down the group because :

New shells are being added, this increases the distance between the

outer most electrons and the nucleus. 1 3

RF/RR (A)-(200)-9046 (MA)-CHEM [ Turn over

83-E (Chem.) 6 CCE RF & RR
Qn.
Value Points Total

24. Draw the diagram of arrangement of the apparatus to show the reaction of

zinc granules with dilute sulphuric acid and testing hydrogen gas by

burning. Label the following parts :

i) Zinc granules

ii) Delivery tube.

Reaction of zinc granules with dilute sulphuric acid :

Delivery tube

Zinc
granules

Diagram — 2
Labeling — 1 + 1
2 2 3

25. Write the balanced chemical equation for the following chemical reactions :

i) Heat
Calcium carbonate  → Calcium oxide + Carbon dioxide

ii) Hydrogen + Chlorine → Hydrogen chloride

CCE RF & RR 7 83-E (Chem.)

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Value Points Total

iii) Magnesium + Hydrochloric acid → Magnesium chloride +

Hydrogen.

OR

Which type of chemical reaction takes place when an iron nail is

dipped in copper sulphate solution ? Why ? Write a balanced chemical

equation for this chemical reaction.

i) CaCO 3 Heat
 → CaO + CO 2 1

ii) H 2 + Cl 2 → 2HCl 1

iii) Mg + 2HCl → MgCl 2 + H 2 . 1
3

OR

Chemical displacement reaction. 1

Because more reactive iron displaces copper from copper sulphate

solution. 1
Fe + CuSO 4 → FeSO 4 + Cu. 1 3

XI. Answer the following question : 1×4=4

26. a) What are structural isomers ? Write the molecular and structural

formula of butane.

b) What is catenation ? Write general formula for alkenes.

a)

Carbon compounds having same molecular formula but different

structural formulae 1
1
Molecular formula of butane is C 4 H 10
2

RF/RR (A)-(200)-9046 (MA)-CHEM [ Turn over

83-E (Chem.) 8 CCE RF & RR
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Structural formula of butane is

1
2

b)

Carbon has unique ability to form bonds with other atoms of

carbon, giving rise to large molecules. 1
General formula for alkene is C n H 2n 1
4