Aqa gcse chemistry 2017 unofficial mark scheme

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UnitedNations
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Which questions do you remember and what do you think are the answers?


1a) Explain why the atomic number is the same for all of these atoms?
These are atoms of the same element with the same number of protons.

Why is the mass number different?
Each atom has different numbers of neutrons as they are isotopes.

Finish the sentence in terms of subatomic particles (3 marks): In the nucleus, there a protons each with a +1 charge. Therefore, due to this, the overall charge of the nucleus is positive.

Explain why each of these stages is done to cast iron.
Stage 1 (oxygen is blasted in) to remove carbon from the cast iron because the carbon reacts with the oxygen to produce carbon dioxide. Stage 2 is completed to make a strong alloy of the cast iron because the cast iron is too brittle.

Miller Urey question, why could their conclusion not be correct?
Not enough evidence
There are other theories which haven't been disproved yet: Meteors

What happens to the alkanes upon heating in the presence of a catalyst in the liquid paraffin question: Thermal decomposition/cracking

alkanes questions emulsions: Hydrophilic head attracted to water, hydrophilic tail attracted to oil. Oil droplets suspended in water 6 marker on quarrying, drilling and thermal decomposition: Carbon particulates cause global dimming. Carbon dioxide is a strong greenhouse gas and causes global warming. Impurities/ sulfur can react with oxygen to produce carbon dioxide which creates acid rain. Why was carbon dioxide removed before condensing? The carbon dioxide would freeze and so it was removed. Nitrogen can react with oxygen to produce nitrogen oxide which also contributes to acid rain... (? Debatable if this would be counted)
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Haroon-----1
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oi
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UnitedNations
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(Original post by Haroon-----1)
oi
Yes?
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JSjjajsjdjn
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For the Miller Urey question could you say that the gases formed in the atmosphere could not be certain
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UnitedNations
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(Original post by JSjjajsjdjn)
For the Miller Urey question could you say that the gases formed in the atmosphere could not be certain
Sorry, what do you mean the gases formed could not be certain? Which gases, and from when are you referring to?
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JSjjajsjdjn
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(Original post by UnitedNations)
Sorry, what do you mean the gases formed could not be certain? Which gases, and from when are you referring to?
The gases in the early atmosphere that Miller and Urey proposed were there may have not been the definite gases that were in the atmosphere
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charlottekaspp
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In the revision guide it mentioned something about not same amount of amino acids made as there are in atmosphere?? Could this be correct for Urey question
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Taylor_watts07
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i love you
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Illymoha
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Was the answer to the miller Urey question was amino acids because they where looking for amino acids not glyclin
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Illymoha
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(Original post by charlottekaspp)
In the revision guide it mentioned something about not same amount of amino acids made as there are in atmosphere?? Could this be correct for Urey question
Yh that's what I said I wrote the " the statement is wrong because they where looking for amino acids "
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Illymoha
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The answer for the finish the question was and there was 6 positive protons therefore there is no overall charge
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Phil_mitchell
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(Original post by JSjjajsjdjn)
For the Miller Urey question could you say that the gases formed in the atmosphere could not be certain
that's what I wrote...
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iamawesome1404
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(Original post by Illymoha)
The answer for the finish the question was and there was 6 positive protons therefore there is no overall charge
the neutrons have no charge tho so the overall charge of the nucleus is positive
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Tibby_
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Is it higher or foundation?
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turtleturtlex
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(Original post by Tibby_)
Is it higher or foundation?
I think it's foundation because I just had a mini heart attack reading about emulsifiers bc i swear i did not talk about them AT ALL
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