NCEA Level 1 Science (90189) 2010 — page 1 of 2
Question
ONE
Achievement
TWO properties, chemical or physical.
Eg.
It has a low reactivity
OR
It is malleable / ductile.
OR
It has a high melting point.
Achievement with Merit Achievement with Excellence
Explains how one physical and one chemical property makes it useful for water pipes.
Eg.
It is not a reactive metal so will not react with water and oxygen readily.
AND
It is malleable, so can be changed into the shape required.
Not ductile
Discusses BOTH chemical and physical properties which make it suitable for water pipes.
Eg.
Because it is not reactive the pipes will last a long time/not contaminate water supply as they will not react with the water etc.
AND
Because it is malleable it can be changed into the required shape, which is good for use in pipes as they are required to bend around corners etc.
Sufficiency
TWO
1 = A
ONE of four correct:
Al
2
O
3
OR
THREE of the following electron configurations:
Aluminium 2.8.3
Aluminium ion 2.8
Oxygen 2.6
Oxygen ion 2.8
OR
Aluminium loses electrons to form positive ions.
OR
Oxygen gains electrons to form negative ions.
NB. Evidence may come from three correct diagrams.
Sufficiency 1 = A
1 = M 1 = E
TWO of three explanations correct:
Eg.
Because aluminium has three electrons in its outer (valence) shell, it loses 3 electrons, giving it a full outer shell / becomes stable, gaining a positive charge.
OR
Each oxygen has 6 electrons in its outer (valence) shell so giving it 2 electrons gives it a full outer shell / becomes stable gaining a negative charge.
OR
An aluminium ion has a charge of
+3, while an oxide ion has a charge of –2, therefore three oxide ions are required to two aluminium ions, so that the final formula is neutral.
Ion formation and stable outer shell plus discusses why two aluminium ions are needed for every three oxide ions in terms of electron transfer, and/or balancing of charge to achieve a neutral compound .
Eg.
Aluminium loses three electrons, so it has a full outer shell and a +3 charge.
Oxygen gains two electrons to gain a full outer shell and so it has a –2 charge. As the compound is neutral, three oxide ions are required to balance out the two aluminium ions as 3

–2

2

+3.
NB. Evidence may come from diagrams showing electron transfer.
1 = M 1 = E

NCEA Level 1 Science (90189) 2010 — page 2 of 2
THREE ONE of four correct:
Eg.
Bubbling / fizzing / explodes/catches fire / moves around fizzing / sodium disappears (not vigorous).
OR
Indicator colour before sodium added is green / after sodium is added it is purple /blue
OR
Sodium + water → sodium hydroxide + hydrogen
(1 of 2 products)
OR
Unbalanced symbol equation
Correct unbalanced symbol equation
AND explains link between colour change and reaction.
2Na + 2H
2
O → 2NaOH + H
2
(does not need to be balanced)
AND
The indicator changes from green to purple, as initially the water is neutral which is green in UI, and then NaOH / base is produced when the sodium is reacted making UI purple/blue.
Explains the link between the colour change and reaction.
AND correctly balanced symbol equation
Eg.
2Na + 2H
2
O → 2NaOH + H
2
AND
The indicator changes from green to purple, as initially the water is pH 7, which is neutral and green in UI, and then in the reaction NaOH is produced, which is a pH greater than 7 and a base making UI purple / blue.
Sufficiency
FOUR
1 = A 1 = M 1 = E
ONE of four correct:
Fizzing/ bubbling,/gas given off
OR
Sodium hydrogen carbonate disappears /
Solution becomes clear or colourless.
OR
Sodium hydrogen carbonate + sulfuric acid → sodium sulfate + carbon dioxide + water
(2 of 3 products)
OR
Unbalanced symbol equation
Unbalanced symbol equation
AND observation.
OR Explains the observation in terms of the products of the reaction AND correct word equation.
EITHER
NaHCO
3
+ H
2
SO
4
→ Na
2
SO
4
+
H
2
O + CO
2
AND observation
OR
Explains that the fizzing is a result of carbon dioxide being formed.
AND correct word equation.
OR
Explains that the Na
2
SO
4
is soluble, so final solution is clear / colourless.
AND correct word equation.
Completely balanced symbol equation
AND explains the link between the observations and the products.
Eg.
2 NaHCO
3
+ H
2
SO
4
→ Na
2
SO
4
+ 2 H
2
O
+ 2 CO
2
AND
Explains that the fizzing
(effervescence) is a result of carbon dioxide being formed.
OR
Explains that the Na
2
SO
4
is soluble, so final solution is clear / colourless.
1 = M 1 = E Sufficiency
Judgement Statement
1 = A
Achievement Achievement with Merit
2 M + 1 A
Achievement with Excellence
2 E + 1 A 3 A
OR
2 M