Exam practice answers

[Pages:16]Exam practice answers

Biology

Chapter 1 Cells

1 (a) (i) A ? chloroplasts; B ? cell membrane;

C ? cell wall

[3]

(ii) B; D; E

[3]

(b) Nucleus; cytoplasm

[2]

(c) Plasmids; non-cellulose cell wall

[2]

2 (a) Add water/iodine; add a coverslip; place the

slide on the microscope stage and focus at

low power

[3]

(b) The tissue is taken from part of an onion

plant that grows underground

[1]

Chapter 2 Photosynthesis and plants

1 (a) carbon dioxide + water >

glucose + oxygen

[2]

(b) (i) Chlorophyll

[1]

(ii) Chloroplasts

[1]

(c) A reaction in which energy is absorbed [1]

2 (a) (i) Leave in a dark place for 48 hours [1]

(ii) To ensure that any starch present is only

produced during the investigation (to make

the investigation valid)

[1]

(b) Add the very hot/boiling water from an

electrical kettle and do not use Bunsen

burners as ethanol is flammable

[1]

(c) To remove chlorophyll; to make any colour

change with iodine easier to see

[2]

3 Any four from:

? At A photosynthesis is occurring much faster than respiration

? So more carbon dioxide absorbed from atmosphere

? As gets closer to end of day (B) light levels reduce

? So less/no photosynthesis

? More respiration than photosynthesis

results in carbon dioxide being added to the

atmosphere

[4]

4 (a) (i) Palisade mesophyll

[1]

(ii) Layer X is closer to light; has cells

packed more tightly together; has more

chloroplasts

[3]

(b) (i) Guard cells

[1]

(ii) To open and close the stomatal pore [1]

Chapter 3 Food and energy

1 (a)

Initial End colour if food [3]

Reagent colour present

Blue-black

Blue

Ethanol

(b) Benedict's

[1]

2 (a) Amino acids

[1]

(b) In each protein the amino acids can be

built up in a different sequence

[1]

(c) (i) Antibody/enzyme/other appropriate

example

[1]

(ii) Muscle/other appropriate example

[1]

3 (a) temperature rise = 47

energy = 25 ? 47 ? 4.2 = 4935

[2]

(b) Hold the food the same distance away from

the boiling tube

[1]

(c) Heat energy lost to the air/used in heating

the glass/left in burned food remains

[1]

Chapter 4 Enzymes and digestion

1 (a) Enzymes are biological catalysts; that speed

up the rates of reactions

[2]

(b)

Food digested Products of [3]

Enzyme (substrate) digestion

Glucose

Protease

Fat

(c) Only one substrate; can fit the active site of an

enzyme

[2]

2 (a) (i) 40?C

[1]

(ii) Low rates of collision between substrate

and enzyme; due to reduced kinetic

energy at low temperature

[2]

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(iii) Reduced enzyme activity as higher

temperatures denature the enzyme;

substrate is no longer able to fit the active

site

[2]

(b) Inhibitor is same general shape as substrate

molecule; so can fit into the active site,

preventing the substrate molecule fitting;

which reduces enzyme activity

[3]

Chapter 5 The respiratory system and cell respiration

1 (a) glucose + oxygen

>carbon dioxide + water + energy

[2]

(b) Lactic acid is produced in muscle and alcohol

in yeast; in yeast carbon dioxide is produced

but not in muscle

[2]

2 Exercise causes the rate of breathing to increase; as the body (muscle) cells require more oxygen; for the increased respiration taking place [3]

3 (a) (i) Increased area across which gases can

diffuse

[1]

(ii) Many alveoli

[1]

(iii) One layer of alveolar cells; one layer of

cells in capillaries

[2]

(b) The cells surrounding the air spaces use up

oxygen in respiration; creating a concentration

gradient of oxygen (less oxygen in spaces than

atmosphere)

[2]

Chapter 6 Coordination and control

1 (a) (i) Association neurone

[1]

(ii) Synapse

[1]

(iii) Spinal cord

[1]

(iv) A

[1]

(v) B

[1]

(b) Shortest possible nerve pathway; as bypasses

the brain

[2]

2 (a) Messenger; blood

[2]

(b) (i) Pancreas

[1]

(ii) A meal rich in carbohydrate

[1]

(iii) Glucose converted to glycogen; more

glucose absorbed from blood

(and respired)

[2]

3 (a) (i) (141 ? 94) = 47

(47/94) ? 100 = 50%

[2]

(ii) Type 1 is also increasing over

time/there are more patients

with type 2 diabetes than type 1

[1]

(iii) Any two from:

? Too much sugar in the diet

? Increase in obesity

? Less exercise being taken

[2]

(b) Any two from:

? Eye damage

? Kidney damage

? Heart disease

? Strokes

[2]

4 (a) Urea

(b) (i) Controlling the water balance in

the body

[1]

(ii) The body loses a lot of water in sweat;

so more water is reabsorbed in the

kidneys

[2]

(iii) The more concentrated the blood the

more ADH released; so more water

reabsorbed by the kidney

[2]

5 (a) (i) Phototropism

[1]

(ii) Any two from:

? More light

? More photosynthesis

? More growth

[2]

(b) Auxin produced in the tip; and passes down

the shaded side of the stem; cells on shaded

side grow more (become longer)

[3]

Chapter 7 Ecological relationships and energy flow

1 (a) The number of individuals of a particular

species in an area

[1]

(b) Use random numbers to position a number

(e.g. 20) of quadrats; calculate the average

number of daisies in the quadrats; multiply

the average per square metre by the number

of square metres in the playing field (or

equivalent calculation)

[3]

2 (a) Flow of energy/showing what eats what [1]

(b) An animal that feeds on producers

[1]

(c) 3

[1]

3 (a) Photosynthesis

[1]

(b) Fossilisation

[1]

Chapter 8 Osmosis and plant transport

1 Put solution A into Visking tubing and tie the ends tightly; dry the surface of the Visking tubing and weigh; place the Visking tubing into a beaker containing solution B; after a few hours remove the

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Visking tubing from the beaker, dry and re-weigh; if the Visking tubing gained in mass then it contained 10% sucrose (as water had moved by osmosis from the 5% sucrose to the 10% sucrose) /if it lost mass then it contained the 5% sucrose (as water had moved by osmosis out of the Visking tubing) [5]

2 (a) (i) 20%; decrease [2]

(ii) The initial masses are different

[1]

(iii) Any two from:

? Same type and size of plant

? Plants given same amount of water (before the investigation)

? Same temperature

? Same humidity

? Same light intensity.

[2]

(iv) The plant in windy conditions lost more

mass; more water lost in transpiration;

windy conditions increase the rate of

evaporation

[3]

(b) Plant cells are more concentrated than their

surroundings; water enters the cells by

osmosis; pushing the cell membrane against

the cell wall, making the cell firm

[3]

3 (a) (i) A ? The carrot cylinder lost water by osmosis; as water moved down the concentration gradient (from carrot to the solution)

B ? There was no change in mass as there

was no overall movement of water in or

out of the carrot cylinders; as the carrot

cylinders and the solution were at the

same concentration

[4]

(ii) Change in length only measures change

in one plane (mass measures the entire

change); balances are more accurate than

using a ruler to measure length (particularly

if the edges are not straight)

[2]

(iii) Same type/age of carrots/carrots cut in

same plane/carrot cylinders the same

thickness

[1]

(b) Any two from:

? Support

? Transport

? Transpiration

? Photosynthesis

[2]

Chapter 9 The circulatory system

1 (a) (i) To carry oxygen

[1]

(ii) Biconcave shape; gives a larger surface area for absorbing oxygen

and/or

No nucleus; more space for carrying haemoglobin

and/or contain iron; to help carry the

oxygen

[4]

(b) They convert fibrinogen to fibrin; causing

blood clotting and scab formation

[2]

2 (a) (i) Provides strength

[1]

(ii) Allows the artery to expand and recoil; as

blood pulses through

[2]

(b) The blood is under less pressure in the renal

artery so the renal artery will expand (and

recoil) less

[1]

(c) Pulmonary artery

[1]

3 (a) (Right atrium) ? right ventricle ? pulmonary

artery; lungs; pulmonary vein ? left atrium ?

(left ventricle)

[3]

(b) Coronary arteries

[1]

4 (a) (i) 108 ? 68

= 40

[2]

(ii) 5 minutes

[1]

(iii) Any two from:

? Lower resting heart rate

? Doesn't rise as high

? Shorter recovery time (returns to normal

faster)

[2]

(b) Strengthens the heart muscle; increased

cardiac output when at rest

[2]

Chapter 10 DNA, cell division and genetics

1 (a) All the DNA in an individual

[1]

(b) (i) Only adenine will pair with thymine; only

cytosine will pair with guanine

[2]

(ii) The sequence of DNA; along the coding

strand is different in everyone

[2]

(c) Each sequence of three bases; codes for a

particular amino acid;

[2]

2 (a) Mitosis produces cells with chromosomes that

are genetically identical to each other; and to

the parent cells; meiosis produces cells with

half the number of chromosomes of the parent

cell; and these cells are genetically different

from each other

[4]

(b) Either chromosome in a pair of chromosomes

can combine with either of the chromosomes

in another pair in gamete formation (and so on

for all 23 pairs in humans); this is independent

assortment

[2]

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3 (a) (i) 3:1

[1]

(ii) Random which gametes from the male combines with each female gamete [1]

(b) Let R = red flowers; r = white flowers

R

r

R RR Rr

r Rr rr

Gametes [2]; offspring [1]

[3]

4 (a) 3

[1]

(b) Every generation is affected/no examples

of an individual having Huntington's disease

without a parent having the condition

[1]

(c) 1 in 2 chance of next child having Huntington's

disease; 1 in 2 chance of being a boy; so

overall chance = 1 in 4

[3]

5 (a) plasmid ? human gene ? bacterium

[1]

(b) The plasmid is cut; using restriction enzymes;

same enzymes for both human DNA and

plasmid; to allow complementary sticky ends

to form

[4]

(c) Any two from:

? Can produce the large amounts required

? Human insulin is slightly different in structure from the insulin of other animals

? The risk of spreading viruses when using animal insulin

? Many people with diabetes are ethically

opposed to using animal insulin

[2]

Chapter 11 Reproduction, fertility and contraception

1 (a) To produce sperm

[1]

(b) (Testes) ? sperm tubes; prostate; urethra in

penis

[3]

(c) Any two from:

? Are haploid

? Tail/flagellum for swimming (to the female gamete)

? Mitochondria for energy production [2]

2 Any three from:

? Fertilised egg (zygote) passes from the oviduct into the uterus

? Zygote divides by mitosis

? To form a ball of cells/embryo

? Implants into the uterine lining/lining of

uterus wall

[3]

3 (a) The release of an egg/ovum; by an ovary [2]

(b) Oestrogen stimulates ovulation; promotes repair of the uterine wall; progesterone continues the build-up of the uterine lining after ovulation (in preparation forpregnancy) [3]

4 (a) To promote the release of eggs/ova by the

ovaries; to ensure the uterine lining

is built up

[2]

(b) Any two from:

? Cost of hormone treatment

? Extraction of eggs/ova is a very specialised role (specialist staff and equipment)

? Placing embryos in uterus is a very specialist role (specialist staff and equipment)

? Any other appropriate answer

[2]

(c) Fertilisation in the laboratory/outside the

body

[1]

5 (a) The number of vasectomies increases with age until ages 40?49; then falls with age [2]

(b) Men aged 20?24 may not be sure that they do

not want children later/men aged 40?49 may

already have a family/are clearer about their

life path/other appropriate answer

[1]

(c) Sperm tubes are cut; sperm cannot travel to

the penis/leave the male body

[2]

Chapter 12 Variation and selection

1 (a) Individuals can be placed into distinct groups

easily with no overlap

[1]

(b) Tongue rolling/hand dominance/other

appropriate answer

[1]

2 Only the fastest predators caught prey; as prey

becoming faster so harder to catch; so only those

predators best adapted (i.e. fastest) survived and

reproduced (passing their genes on)

[3]

3 In industrial areas the black moths are better

camouflaged/lighter forms less well camouflaged;

the lighter moths are more likely to be predated/

black forms less likely to be predated; number of

black moths increases over time/number of light

moths decreases over time

[3]

4 Similar ? the best males and best females are used in the breeding process/it is humans, rather than nature, doing the selection

Difference ? the process is much faster (several

generations are not required to produce high ?

quality offspring

[2]

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Chapter 13 Health, disease, defence mechanisms and treatments

1 (a) Tuberculosis; it is a bacterial disease and the

other diseases are viral

[2]

(b) The doctor was not clear as to exactly

which type of bacteria caused the infection;

an antibiotic would work quicker than a

vaccination

[2]

2 (a) Antibodies are a complementary shape to the

antigens on a microorganism; they latch on the

microorganisms; immobilising them/preventing

them from spreading around the body

[3]

(b) Active

[1]

(c) Phagocytes engulf harmful microorganisms;

and digest them

[2]

3 (a) Any two from:

? Excess dietary fats

? Smoking

? Lack of exercise

? Stress

[2]

(b) The stent is pushed to the site of a blockage in

a blood vessel; and then expanded to hold the

vessel open

[2]

4 (a) Nicotine

[1]

(b) Carbon monoxide combines with the red blood

cells; preventing oxygen from combining;

therefore less oxygen is carried to the body

cells for respiration

[3]

5 (a) Benign and malignant

[1]

(b) Benign is encapsulated/doesn't spread around

the body (or converse)

[1]

Chemistry

Chapter 14 Atomic structure

1 number of protons in (the nucleus of) an atom [1]

2 (a) proton: relative mass = 1 and relative charge =

+1

1

[1]

(b) electron: relative mass = 1840 and

relative charge = -1

[1]

(c) neutron: relative mass = 1 and relative charge = 0

[1]

3 Atoms of the same element/with the same number

of protons [1] but with a different mass number/

different number of neutrons [1].

4 Atoms contain the same number of protons and

electrons

[1]

5 (a) 2,8,5

[1]

(b) 2,1

[1]

(c) 2,6

[1]

(d) 2,8,8,1

[1]

(e) 2,8,8

[1]

(f) 2

[1]

(g) 2,8,3

[1]

(h) 2,8,1

[1]

6 (a) 2,8

[1]

(b) 2,8

[1]

(c) 2,8

[1]

(d) 2,8

[1]

(e) 2,8,8

[1]

7 (a) Al3+ O2-

F-

[1]

(b) Al3+

[1]

(c) Cl-

[1]

(d) hydride ion

[1]

8 (a) 3-

[1]

(b) phosphorus

[1]

(c) phosphide

[1]

9 20 protons and 20 neutrons [1] in the

nucleus [1]

20 electrons [1] arranged 2,8,8,2 [1]

10 relative atomic mass =

(5.8

?

54)

+

(91.8

?

56) + (2.2 100

?

57)

+

(0.2

?

58)

[1]

= 5591 = 55.91 [1] = 55.9 [1]

100

to 1 decimal place

Chapter 15 Bonding, structures and nanoparticles

1 A mixture of two or more elements, at least one

of which is a metal [1] and the resulting mixture

has metallic properties [1].

2 any two from: conducts electricity/light/faster

recharge/less required

[2]

3 attraction [1] between oppositely charged ions [1]

4 (a) ionic

[1]

(b) covalent

[1]

(c) metallic

[1]

5 (a) top unbonded pair of electrons labelled [1]

(b) covalent

[1]

(c) van der Waals' forces of attraction

[1]

(d) NH3

[1]

6 pair of electrons [1] shared between two atoms

[1]

7 (a)

??

[1]

Cl ? Cl

? ?

??

chlorine, Cl2

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(b)

[1]

??

H?

O

? ?

? H

water, H2O

(c)

[1]

O? C? O

?

?

carbon dioxide, CO2 O=C=O

8 The van der Waals' [1] forces of attraction

between the molecules are weak [1] and require

little energy to break [1].

9 Each carbon atom [1] covalently [1] bonded to

four [1] other carbon atoms in a tetrahedral [1]

arrangement, and the structure is giant [1].[max. 3]

10 Delocalised electrons [1] can move and carry

charge [1].

11 A regular arrangement/lattice [1] consisting

of layers [1] of positive ions/cations [1] held

together by metallic bonding, which is the

attraction between the positive ions and the

delocalised electrons [1].

[max. 4]

12 (a) sodium and iron

[1]

(b) sodium, graphene and iron

[1]

(c) ammonia, hydrogen and carbon dioxide [1]

13 (a) In sodium chloride solution the ions [1] are

free to move and carry charge but in solid

sodium chloride the ions cannot move [1].

(b) ionic lattice

[1]

(c) Strong ionic bonds [1] require substantial

energy to break [1].

Chapter 16 Symbols, formulae and equations

1 (a) NaF

[1]

(b) MgO

[1]

(c) K2O

[1]

(d) BaCl2

[1]

2 (a) CuCl2

[1]

(b) ZnO

[1]

(c)CuSO4

[1]

(d) Fe(OH)3

[1]

3 sodium carbonate = Na2CO3 [1]; sodium

hydrogencarbonate = NaHCO3 [1]

4 (a) carbon dioxide

[1]

(b) potassium nitrate

[1]

(c) copper(ii) carbonate

[1]

(d) hydrogen fluoride

[1]

(e) magnesium sulfate

[1]

5 (a) (NH4)2SO4

[1]

(b) SO2

[1]

(c) Ca(HCO3)2

[1]

(d) Al2(SO4)3

[1]

6 S2O32-

[1]

7 (a) hydroxide

[1]

(b) oxide

[1]

(c) chloride

[1]

(d) aluminium

[1]

(e) sulfate

[1]

8 (a) 2KOH + H2SO4 K2SO4 + 2H2O

[3]

(b) 2Ca + O2 2CaO

[3]

(c) 2Al + 3Cl2 2AlCl3

[3]

9 CuCO3 CuO + CO2

[2]

10 2C2H6 + 7O2 4CO2 + 6H2O

[3]

(accept:C2H6 + 3?O2 2CO2 + 3H2O)

11 (a) BaCl2(aq) + K2SO4(aq) BaSO4(s) +

2KCl(aq)

[4]

(b) Ba2+ + SO42- BaSO4

[2]

12 (a) Ca(OH)2 + 2HCl CaCl2 + 2H2O

[3]

(b) Al2O3 + 3H2SO4 Al2(SO4)3 + 3H2O

[3]

(c) Zn + 2HCl ZnCl2 + H2

[3]

13 N2 + 3H2 2NH3

[3]

14 Zn2+ + 2OH- Zn(OH)2

[3]

15 (a) (i) Mg + Cu2+ Mg2+ + Cu

[2]

(ii) Zn + 2H+ Zn2+ + H2

[3]

(iii) CO32- + 2H+ CO2 + H2O

[3]

(b) (i) Mg Mg2+ + 2e- and Cu2+ + 2e- Cu

[6]

(ii) Zn Zn2+ + 2e- and 2H+ + 2e- H2

[6]

Chapter 17 The periodic table

1 (a) alkali metals

[1]

(b) alkaline earth metals

[1]

(c) halogens

[1]

(d) noble gases

[1]

2 K K+ + e-

[2]

3 phosphorus, P

[1]

4 Any four from: floats/fizzes/moves about the

surface/heat released/colourless solution

formed/disappears/lilac flame/crackle or

explosion

[4]

5 (a) yellow gas

[1]

(b) yellow-green gas

[1]

(c) red-brown liquid

[1]

(d) grey-black solid

[1]

(e) colourless gas

[1]

6 (a) Rb+

[1]

(b) I-

[1]

(c) K+

[1]

(d) F-

[1]

7 group 6

[1]

8 (a) nitrogen [1]; oxygen [1]; fluorine [1];

bromine [1]

(b) carbon/sulfur

[1]

(c) sodium

[1]

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(d) iron

[1]

(e) oxygen [1]; nitrogen [1]; fluorine [1]

9 shiny surface goes dull

[1]

10 fluorine

[1]

11 (a) white [1]; (b) grey-black [1]; (c) black [1];

(d) blue [1]; (e) green [1]

12 Cl2 + 2e- 2Cl-

[3]

13 any three from: large trough of water/small

piece of sodium/safety screen/gloves/glasses/

tongs to handle sodium/remove oil from surface

of sodium

[3]

14 (a) 2Na + 2H2O 2NaOH + H2

[3]

(b) Sodium is less dense than water.

[1]

15 any two from: in order of atomic mass (weight)/

no noble gases/no block of transition metals/

no atomic number/fewer elements or gaps/no

actinides or lanthanides

[2]

Chapter 18 Quantitative chemistry I

1 carbon-12

[1]

2 (a) 98

[1]

(b) 74

[1]

(c) 342

[1]

(d) 138

[1]

(e) 162.5

[1]

3 moles CaCO3 = 5/100 = 0.05

[1]

moles CaO = 0.05

[1]

mass CaO = 0.05 ? 56 = 2.8g

[1]

4 moles Mg = 1.2/24 = 0.05

[1]

moles MgO = 0.05

[1]

mass MgO = 0.05 ? 40 = 2g

[1]

5 (a) moles of Fe2O3 = 40/160 = 0.25

[1]

(b) moles of Na = 46/23 = 2

[1]

(c) limiting reactant = Fe2O3

[1]

(d) moles of iron = 0.25 ? 2 = 0.5

[1]

(e) mass of iron = 0.5 ? 56 = 28g

[1]

6 (a) (36/171) ? 100 [1] = 21.1% [1]

(b) (180/286) ? 100 [1] = 62.9% [1]

7 H2O2

[1]

8 (a) moles P = 1.55/31 = 0.05

[1]

moles of PCl5 formed = 0.05

[1]

mass PCl5 (theoretical yield) = 0.05 ? 208.5

= 10.425g

[1]

(b) (8.34/10.425) ? 100 [1] = 80% [1]

(c) side reactions/not all phosphorus reacts [1]

Chapter 19 Acids, bases and salts

1 a soluble base [1]

2 any two from: copper(ii) oxide/copper(ii)

carbonate/copper(ii) hydroxide

[2]

3 (a) purple/dark blue [1]; 12?14 [1]

(b) red [1]; 0?2 [1]

(c) blue [1]; 9?11[1]

(d) yellow or orange [1]; 3?6 [1]

(e) green [1]; 7 [1]

4 H+

[1]

5 Any metal oxide or metal hydroxide, such as

magnesium oxide, copper(ii) oxide, sodium

hydroxide etc.

[max. 2]

6 0.5mol/dm3

[1]

7 H+(aq) + OH-(aq) H2O(l)

[3]

8 (a) Mg + 2HCl MgCl2 + H2

[3]

(b) Mg(OH)2 + 2HCl MgCl2 + 2H2O

[3]

(c) CaCO3 + 2HCl CaCl2 + CO2 + H2O

[3]

9 (a) heat released [1]; bubbles of gas [1]; solid

disappears [1]; colourless solution [1][max. 3]

(b) bubbles of gas [1]; green solid disappears

[1]; solution changes from colourless to

blue [1]; heat released [1]

[max. 3]

10 sodium chloride

[1]

11 (a) red

[1]

(b) red

[1]

(c) orange

[1]

12 hydrogen [1]; hold a lit splint at the mouth of a

tube of it [1]; listen for pop [1]

Chapter 20 Chemical analysis

1 (a) solid that dissolves in a solvent

[1]

(b) liquid in which the solute dissolves

[1]

(c) mixture of the solute dissolved in the solvent

[1]

2 Add water [1] then filter through filter paper [1].

Sand is the residue [1]; water is the filtrate [1].

3 fractional distillation

[1]

4 (a) 3

[1]

(b) water or other suitable solvent

[1]

(c) 2

[1]

(d) 1 and 4

[1]

(e) 1

[1]

(f) not soluble

[1]

(g) solvent front

[1]

5 (a) B = filter paper [1]; C = filter funnel [1];

D = conical flask [1]

(b) residue

[1]

(c) filtrate

[1]

(d) sand mixed with water

[1]

6 white to blue [1]

7 N ichrome wire [1], dipped in concentrated

hydrochloric acid [1]. Place in sample and

heat sample in blue Bunsen burner flame [1].

Observe yellow/orange flame colour [1] for

sodium ions.

Chapter 21 Reactivity series of metals

1 hydrogen

[1]

2 any four of: floats/moves about the surface/fizzes/

lilac flame/eventually disappears/explodes or

crackles/heat released/colourless solution formed

[4]

CCEA GCSE Science Double Award 7

Exam practice answers

3 2K + 2H2O 2KOH + H2

[3]

4 any three from: red-brown solid appears/blue

solution/fades to colourless/heat released [3]

5 By heating [1] damp mineral wool [1].

6 (a) Cu + 2AgNO3 Cu(NO3)2 + 2Ag

[3]

(b)

nitrate

ion/

NO

- 3

[1]

(c) Cu + 2Ag+ Cu2+ + 2Ag

[3]

7 Aluminium has a protective oxide layer.

[1]

8 Grey solid [1] burns with a bright white light

[1], forming a white solid [1].

9 (a) calcium

[1]

(b) calcium

[1]

(c) calcium, aluminium, zinc, copper

[1]

10 2Ca + O2 2CaO

[3]

11 magnesium, manganese, chromium, nickel [1]

12 2Cr + 3Ni(NO3)2 2Cr(NO3)3 + 3Ni

[3]

13 Mg + Mn2+ Mg2+ + Mn

[2]

14 All nitrates are soluble in water.

[1]

Chapter 22 Redox, rusting and iron

1 Nitrogen gains hydrogen [1] and gain of hydrogen

is reduction [1].

2 (a) hydrogen

[1]

(b) oxygen

[1]

3 h aematite/iron ore [1]; coke/carbon [1];

limestone/calcium carbonate [1]; hot air [1]

4 magnesium/zinc

[1]

5 (a) hydrated iron(iii) oxide [1]

(b) Redox is oxidation and reduction occurring

simultaneously in the same reaction. [1]

6 oxygen [1]; loss [1]; oxygen [1]; gain [1]

7 (a) Zn Zn2+ + 2e-

[3]

(b) Cu2+ + 2e- Cu

[3]

(c) Zn equation

[1]

8 Mg Mg2+ + 2e- [3]; oxidation [1]

2H+ + 2e- H2 [3]; reduction [1] 9 Magnesium is oxidised [1]; zinc ions are

reduced [1].

10 water/moisture [1]; air/oxygen [1]

11 any two of: painting/oiling/greasing/plastic

coating/suitable metal plating or galvanising [2]

12 Fe2O3 + 3CO 2Fe + 3CO2

[3]

13 Calcium carbonate undergoes thermal

decomposition.

[1]

CaCO3 CaO + CO2

[2]

C alcium oxide reacts with silicon dioxide to form

calcium silicate/slag.

[1]

CaO + SiO2 CaSiO3

[2]

14 (a) Carbon gains oxygen [1] and gain of oxygen

is oxidation [1].

(b) CO2 + C 2CO

[3]

15 Magnesium is more reactive than iron [1], so

magnesium reacts first [1].

Chapter 23 Rates of reaction

1 manganese(iv) oxide

[1]

2 sulfur

[1]

3 gas syringe

[1]

4 2H2O2 2H2O + O2

[3]

5 rate increases

[1]

6 A substance that increases the rate of a

chemical reaction [1] without being used up [1].

7 hydrogen

[1]

8 size of solid particles/presence of a catalyst [1]

9 change in mass against time [1]; using a conical

flask on a balance[1]; or change in gas volume

against time [1]; in a gas syringe [1]

10 Hydrogen ions/particles move faster/have more

energy [1], so there are more collisions [1] and

more successful collisions/more collisions with

higher than activation energy [1] in a given period

of time [1]; rate increases [1].

[max. 4]

11 (a) 80 seconds

[1]

(b) 80cm3

[1]

(c) 25 seconds

[1]

(d) starts at (0,0), remains higher and levels

off at the same level

[1]

(e) starts at (0,0), remains lower and levels

off at the same level [1]

Chapter 24 Equilibrium

1 H2 + Br2 2HBr

[3]

2 temperature [1]; pressure [1]

Chapter 25 Organic chemistry

1 (a) C2H6

[1]

(b) C2H4

[1]

(c) C4H10

[1]

(d) CH4

[1]

2 orange/brown solution changes to colourless [1]

3compounds containing only carbon and

hydrogen

[1]

4 (a) propane

[1]

(b) but-2-ene

[1]

(c) propan-1-ol

[1]

5 C2H5OH + 3O2 2CO2 + 3H2O

[3]

6 ethane

[1]

7 fractional distillation [1]

8 2CH3COOH + Mg (CH3COO)2Mg + H2

[3]

9 A family of organic compounds with the same

general formula [1], which differ by a CH2 unit [1]. They show a gradation in their physical properties

[1] and similar chemical properties [1]. [max. 3]

10 (a) polythene

[1]

(b) PVC

[1]

8 CCEA GCSE Science Double Award

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