2020_Combined science_olevel_nov_paper2

Extracted Content: 2020_Combined science_olevel_nov_paper2

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Candidate Name

Far Performance Mrwsetement

COMBINED SCIENCE
PAPER 2 Theory

NOVEMBER 2020 SESSION

Additional materials:
Answer sheets

Calculator (Optional)
String

The Periodic Table is provided on page 15,

2 hours

Time
INSTRUCTIONS TO CANDIDATES

Write your name, centre number and candidate number in the spaces at the top.

Section A

Answer all questions.

write your answers in the spaces provided on the question
paper.

Section B

Answer any two questions.

Write your answers on the separate answer paper provided.
Section C

Answer any two questions.

Write your answers on the separate sheets provided,
Section D

Answer any two questions.

Write your answers on the separate answer sheets provided,

INFORMATION FOR CANDIDATES
The number of marks is given in brackets [ ] at the end of
each question.

This question paper consists of 16
Copyright: Zimbabwe School Examination

printed

© ZIMSEC N2020

Centre Number

ZIMBABWE SCHOOL EXAMINATIONS COUNCIL

General Certificate of Education Ordinary Level

s Council,

Candidate Number

4003/2

2 hours

For examiner’s use

[seciona |_|

Section B

Section C

Pages.
N2020.

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(b)

(©)

Section A

Answer all the questions in the spaces provided.

Define the term ecosystem.

State any two physical components of an ecosystem.

1

Draw a food chain, with three trophic levels, involving named organisms

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2. Fig.2.1 shows a cell membrane separating water and sugar solution.

cell membrane

water

sugar solution

(a) @ Explain how osmosis occurs.

(ii) Define the term diffusion.

(b) Blood circulating around the body has plasma, water, platelets, glucose,
red blood cells, carbon dioxide, oxygen and white blood cells.

@ Select two substances that are needed by respiring cells.

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(ii) State the component of blood responsible for blood clotting.

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(c) Explain the importance of blood clotting.

Sulphur dioxide (SO,) reacts with oxygen (O2) to form sulphur trioxide (SOs) during
the manufacture of sulphuric acid as shown in the equation:

280, + 0, — 2803 + heat

(a) State the oxidation state of sulphur in sulphur trioxide.
(i
(b) State the meaning of the symbol =.
[1]
© Write an equation to show the formation of oleum.
[2]
(a) State any two industrial uses of sulphuric acid.

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[2] Fig.4.1 shows the stages involved in the extraction of gases A and B from air. -196 °C =A = = : -186 °C => argon -183°C—=>B compression rapid expansion tower X liquid air Fig.4.1 (a) Name the component that is removed during filtration. [1]

(b) @ Identify the process that occurs in tower X.

Gi) Explain why the air is compressed and expanded rapidly and *
repeatedly.

(©)

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[1]

(d) Identify the gases A and B.
A
B
[2]
(a) A box contains resistors of different sizes. Ten resistors are rated 5 Q, twelve
are rated 8 Q, eight are rated 10 Q and ten are rated 15 Q.
(i) State any one way of presenting the data apart from the description.
[1]
(ii) Calculate the percentage of the resistors rated 15 (2.
[2]

(b) One side of a cube measures 6.0 cm.

Calculate the volume of the cube.

[2]

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(°) Give the most suitable instrument for measuring

(i) the internal diameter of a test tube,

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Gi)

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(b)

@

(ii)

i of energy.
Give a reason why solar energy is called a renewable source ey

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[1)

Explain how solar energy is indirectly used to produce electricity.

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[2]

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7.

(a)

(b)

(a)

(b)

(a)

(b)
©)

Section B

Answer any two questions on the separate answer sheets provided.

(i) State any three methods of contraception. [3]
(ii) Describe how each method stated in (i) prevents fertilisation. 3]
@ Define the term rhizome. fl]
(ii) ‘State any three advantages of reproducing plants by means of
rhizomes. [3]
(i) State any two components of a balanced diet and state one function
for each. [4]
di) Explain the term deficiency disease. {i
(iii) Give any three deficiency diseases, [3]
State any two processes through which energy is lost in food chains and
food webs. 22]
@ Define the term immunity. {1]
(ii) State the two methods by which infants acquire immunity. [2]
Describe the process of vaccination. [4]
Describe any three methods of controlling mosquitoes. [3]
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10. (a)

()

©

10

Section C

Answer any two questions on the separate answer sheets provided.

The reaction between copper oxide (CuO) and hydrogen (H,) involves
oxidation and reduction.

Cu0+H, —- Cut+H,O0
@ Define the term oxidation.

(ii) Identify the reducing agent in the reaction between copper oxide
and hydrogen.
Iron is extracted from iron(II) oxide in the blast furnace.

@ ‘Name any two raw materials that are fed into the furnace from the
top.

(ii) Write a chemical equation for the reaction that produces iron.

(i) Describe, with the help of equations, how slag (calcium silicate)
is formed in the blast furnace.

(ii) State any one metal which is added to iron to make stainless steel.

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[1]

1]

[2]
[2]
[3]
(1)

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11.

12.

(a) Fig.11.1 represents an incomplete electrolytic cell that can be used for copper
plating an iron object.

copper

electrode iron object

electrolyte
Fig.11.1
@ Define the term electrolysis. a
(ii) Name the electrolyte used in the process. (]
(iii) Identify the missing apparatus. [1]

(b) State one change which occurs at the

@ copper electrode, 01]
Gi) iron object. 1]
(c) State two reasons for electroplating iron objects. [2]
(d) Write the half equation for the copper electrode, [3]

3 3
A volume of 0.025 dm of 0.1 mol/dm sodium hydroxide (NaOH ) solution was put
into a flask and a few drops of phenolphthalein indicator eee =e \ alam . oe

0.020 dm of dilute hydrochloric acid (H(C/) was used to completely neutralise sodium
hydroxide solution.

thod of neutralisation used.
(a) ‘Name the me 4003/2 N2020 [1]

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(b)

()

(d)
(e)

12
Explain the purpose of adding phenolphthalein indicator. [1]

Write a chemical equation for the reaction between sodium hydroxide and
hydrochloric acid.

[2]
Give a reason why hydrochloric acid should be handled with care. [1]
Calculate the concentration of the dilute hydrochloric acid. [5]

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13

Section D
Answer any two questions on the separate answer sheets provided.

13, = (a) Explain how a positively charged gold leaf electroscope can be used to test

the charge ona charged rod. [4]
ob) @& Describe how a house is protected by a lightning conductor. [3]
(ii) ‘State any two dangers of lightning. [2]
(iii) State any one safety precaution that should be taken against
lightning. [1]
14. (a) Fig.14.1 shows a model of a hydroelectric power station designed by a
student.
turbine water outlet
Fig.14.1
(i) Describe, using energy changes, how the bulb in the model
lights. [3]
(1) Explain why using a hydr oelectric power station is better than using
a thermal power station. 2]
(b) (i) State the relationship between voltage and current. (1]
(ii) State any two factors that affect resistance of an electrical
conductor. 2
iii) Calculate the current flowing in a circuit if th i
‘ difference across a 2 Q resistor is 6 V, Polenta 2]

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14

15. (a) _—_A pot with water is placed on an electric stove and the water is heated
until it boils.

(i) State the modes of heat transfer involved. [2]

(ii) Describe the modes of heat transfer stated in (a)(i). [3]
(b) The electric stove is marked 2 000 W.

(i) Define the terms electrical power and electrical energy. [2]

(ii) The water in the pot boils after 8 minutes.

Calculate the energy supplied by the electric stove. [3]

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