These are the solutions to semester 3 test in science of 2014.
For more explanations refer to the notes.
1. Sodium chloride is obtained from underground deposits in the Earth’s crust.
Low-sodium salt is a mixture containing both sodium chloride and potassium chloride.
Explain why the Earth’s crust contains the compound sodium chloride and not the
uncombined elements, sodium and chlorine.
Answer: reference to reactivity of elements / compound is more stable ;
State differences between a compound, such as potassium chloride, and a
mixture, such as low-sodium salt.
Answer: compound has elements in fixed proportions / has a formula ;
mixture has no fixed proportions ;
compound has new chemical properties ;
mixture retains the properties of the constituents ;
compound has all constituents chemically bonded ;
mixture does not have chemical bonds between all constituents ;
a mixture can be separated by physical means ;
a compound cannot / can only be separated by chemical means ;
a compound is formed by chemical reaction
a mixture is not formed by chemical reaction ;
Answer: potassium and calcium (both required) /Ca2+ and K+ ;
Deduce the chemical formula of the compound calcium fluoride.
Show how you obtained your answer.
Answer: reference to charge balance / correct electron transfer shown ;
CaF2 ;
The element calcium is formed during the electrolysis of molten calcium chloride.
During this process, calcium ions are converted to calcium atoms on the surface of the
cathode.
Explain why calcium atoms form on the cathode and not on the anode.
Answer: cathode is negative ;
reference to attraction between opposite charges ;
Describe what happens at the surface of the cathode to convert calcium ions to
calcium atoms.
Answer: ions gain electrons ;
each ion gains two (electrons) / is discharged ;
2. Enzymes are made from
A fat.
B hormones.
C proteins.
D starch.
3. What are the main products of photosynthesis?
A carbon dioxide + oxygen
B carbon dioxide + water
C simple sugars + oxygen
D simple sugars + water
4. Which chambers of the heart have the thickest and most muscular walls?
A left atrium and right atrium
B left atrium and right ventricle
C left ventricle and right atrium
D left ventricle and right ventricle
5. How often is an egg usually released from the ovaries of a woman?
A once a week
B once every 14 days
C once every 28 days
D once every 9 months
6. Which is a greenhouse gas that plants help to remove from the atmosphere?
A carbon dioxide
B hydrogen
C methane
D oxygen
7. Which method of separation can be used to obtain pure water from aqueous potassium
chloride?
A chromatography
B crystallisation
C distillation
D filtration
8. Which reaction involves combustion?
A calcium carbonate → calcium oxide + carbon dioxide
B methane + oxygen → carbon dioxide + water
C sodium carbonate + hydrochloric acid → sodium chloride + water + carbon dioxide
D sodium hydroxide + hydrochloric acid → sodium chloride + water
9. A drop of liquid falls on a student’s skin and evaporates quickly.
What is the effect on the skin and the reason for this effect?
A The skin cools because the most energetic molecules escape from the liquid.
B The skin cools because the most energetic molecules remain in the liquid.
C The skin warms because the most energetic molecules escape from the liquid.
D The skin warms because the most energetic molecules remain in the liquid.
10. Which two colors of the visible spectrum of light have the greatest difference in their
wavelengths?
A blue and red
B red and green
C orange and red
D yellow and blue
11. When a computer is switched on, the current rises quickly to 3.1 A and then falls slowly to a
steady value of 1.0 A whilst the computer is in use.
The mains plug for the computer contains a fuse.
Which value of fuse would be suitable to use and would provide the greatest protection?
A 1.0 A
B 3.0 A
C 5.0 A
D 13.0 A
12. Which word equation represents aerobic respiration?
A carbon dioxide + water → glucose
B carbon dioxide + water → glucose + oxygen
C glucose → carbon dioxide + water
D glucose + oxygen → carbon dioxide + water
13. A healthy plant has been in the light. A leaf is taken from it, decolourised and then tested
with
iodine solution.
What colour does the iodine solution become?
A black
B brick red
C green
D pale blue
14. What is the effect of cutting down large numbers of trees?
A Flooding is less likely to occur.
B It increases the amount of carbon dioxide in the air.
C It increases the amount of methane in the air.
D It prevents the extinction of animal species.
15. A ray of light travels from glass into air. The angle of refraction is equal to the angle of
incidence.
What is the angle of incidence?
A 0°
B 45°
C 60°
D 90°
16. Which electromagnetic waves are found immediately either side of the visible region of the
electromagnetic spectrum?
A infrared and ultra-violet
B microwaves and infrared
C microwaves and X-rays
D ultra-violet and X-rays
17. Which substance can enter a plant cell by diffusion?
A carbon dioxide
B cellulose
C protein
D starch
18. A test-tube contains a solution of an enzyme.
Which color is obtained when the biuret test is carried out on this solution?
A blue
B blue-black
C orange
D purple
19. Which two chemical substances are required for photosynthesis?
A carbon dioxide and glucose
B glucose and oxygen
C oxygen and water
D water and carbon dioxide
20. What is a function of the small intestine?
A It allows food to be stored.
B It cuts food into small pieces.
C It provides a large surface area for absorption.
D It provides space for the storage of faeces.
21. Which substance makes up a higher percentage of expired air compared to inspired air?
A carbon dioxide
B nitrogen
C noble gases
D oxygen
22. What is the function of the valves in the heart?
A to prevent blood from flowing backwards
B to pump blood through the heart
C to separate blood cells from plasma
D to separate oxygenated and deoxygenated blood
23. What describes sexual reproduction?
A Diploid gametes form a haploid zygote, offspring genetically dissimilar to parents.
B Diploid gametes form a haploid zygote, offspring genetically similar to parents.
C Haploid gametes form a diploid zygote, offspring genetically dissimilar to parents.
D Haploid gametes form a diploid zygote, offspring genetically similar to parents.
24. Which chemical is a building block for making proteins?
A amino acid
B fatty acid
C glucose
D glycerol
25. A student carries out experiments with zinc and dilute hydrochloric acid.
Which change in conditions makes the reaction slower?
A adding a suitable catalyst
B increasing the concentration of the acid
C increasing the particle size of the zinc
D increasing the temperature
26. Which chemical test shows the presence of water?
A Water has a boiling point of 100 °C.
B Water has a freezing point of 0 °C.
C Water turns anhydrous cobalt chloride from blue to pink.
D Water turns anhydrous copper sulfate from blue to white.
27. Which statements about the complete combustion of methane are correct?
1 The reaction is endothermic.
2 Carbon dioxide is formed.
3 Water is formed.
A 1, 2 and 3
B 1 and 2 only
C 1 and 3 only
D 2 and 3 only
28. Which method is used to extract copper from copper(II) oxide?
A dissolving copper(II) oxide with hydrochloric acid and then filtering
B dissolving copper(II) oxide in water and then filtering
C heating the copper(II) oxide
D heating the copper(II) oxide mixed with carbon
29. As part of a festival, a wooden wheel is set on fire. The burning wheel rolls down a hill.
What is one energy conversion that occurs as the wheel burns and rolls down the hill?
A gravitational to kinetic
B heat to chemical
C kinetic to chemical
D light to gravitational
30. When sweat evaporates, which change of state takes place?
A gas to liquid
B liquid to gas
C liquid to solid
D solid to gas
31. On a summer’s day, hot air rises above hot roofs.
What is the name of this process?
A concentration
B condensation
C conduction
D convection
32. An electronic circuit in a fire alarm makes a loudspeaker vibrate alternately at two different
frequencies.
Which pair of frequencies is suitable to use in the alarm to alert people to the danger of fire?
A 1.5 Hz and 15 Hz
B 15 Hz and 150 000 Hz
C 150 Hz and 15 000 Hz
D 150 000 Hz and 15 000 000 Hz
33. What occurs about two weeks after menstruation?
A the release of a gamete from an ovary
B the release of a gamete from the uterus
C the release of a zygote from an ovary
D the release of a zygote from the uterus
34. The diagram shows five organisms in a food chain.
T→ U→ V→ W→ X
Which organisms are consumers?
A T, U and V
B T, W and X
C T, V and X
D U, V and W
35. Which statements about air are correct?
1 Air contains a small amount of argon which is a noble gas.
2 Air is made up of 78% oxygen and 21% nitrogen.
3 Air contains carbon dioxide which is a product of both respiration and the
combustion of natural gas.
A 1, 2 and 3
B 1 and 2 only
C 1 and 3 only
D 2 and 3 only
36. Which mixture cannot be separated by distillation?
A air
B petroleum
C salt water
D sulfur and iron
37. Which substance conducts electricity?
A CO2(g)
B NaCl (s)
C NaOH(aq)
D S(s)
38. Which pair of gases can be identified using limewater and damp litmus paper?
A carbon dioxide and chlorine
B carbon dioxide and hydrogen
C chlorine and oxygen
D hydrogen and chlorine
39. Which energy resource is non-renewable?
A geothermal energy
B hydroelectric energy
C nuclear energy
D wave energy
40. The International Space Station orbits the Earth in the vacuum above the atmosphere.
The electrical systems in the Space Station produce heat.
How is this heat transferred from the external surfaces of the Space Station into space?
A conduction only
B convection only
C radiation only
D conduction, convection and radiation
41. An electrically charged student produces soap bubbles. When he holds his hand near the
bubbles, they move away quickly from his hand.
For this movement of the bubbles to happen, which statement is correct?
A The bubbles must be negatively charged.
B The bubbles must be positively charged.
C The bubbles must have the opposite charge to the charge on the student.
D The bubbles must have the same charge as the charge on the student.
42. The addition of a harmful substance to the environment is called pollution. Three examples
of pollution caused by human activities are
• acid rain,
• fertilisers entering rivers and lakes,
• the release of too much carbon dioxide into the atmosphere.
(a) Describe how acid rain is caused.
(a) combustion/burning, of (fossil) fuels/coal;
sulfur dioxide produced;
(which) reacts with/dissolves in, water (in atmosphere);
(b) Explain what happens in a lake after large quantities of fertilisers are washed into it.
(b) eutrophication;
increased growth of algae;
blocks light to plants deeper down;
algae/plants, die;
bacteria feed on them/bacteria population increases;
bacteria use oxygen;
removal of oxygen kills fish;
(c) Explain how cutting down forests can result in an increase in the carbon dioxide
concentration in the atmosphere.
(c) reference to (less) photosynthesis;
so less carbon dioxide removed;
trees burned;
producing carbon dioxide;
43. Marble and chalk are two forms of calcium carbonate.
The diagram shows equal masses of lumps of marble and powdered chalk placed in dilute
hydrochloric acid.
The marble takes longer than the chalk to dissolve in the acid.
Why is this?
A Marble is more reactive than chalk.
B Marble is more soluble than chalk.
C The marble has the smaller surface area.
D The marble is more basic.
44. In which test-tube does rusting occur most quickly?
Answer: D
45. The table shows the properties of four substances.
Which substance is an alkali?
Answer: C
46. The positions of elements P, Q, R, S and T in the Periodic Table are shown.
The letters are not the symbols for the elements.
Which element forms an ionic compound with element P?
AQ
BR
CS
DT
47.
Answer: D
48. Molecules of W, X and Y are shown.
Answer: A
49. Copper(II) bromide can be electrolysed in the same way as copper(II) chloride.
Answer: A
50. Metal X reacts rapidly with cold water.
Metal Y does not react with dilute hydrochloric acid.
Metal Y is obtained from its oxide by heating with carbon.
Which row shows the more reactive metal and the type of reaction which metal Y oxide
undergoes when it is heated with carbon?
Answer: B