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Chemistry paper 1 doubts!!

D

D4nyzz

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To2a Bahaa said:
Guys please I need some help in question 36 Nov 2008 paper 1 , why is it that chlorination couldn't remove the fertliliser? And question 13 in NOV 2009 paper 11, can anyone explain it please?
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Chlorination is used to kill the bacteria not to remove the fertilliser.
 
NKPyo

NKPyo

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To2a Bahaa said:
Guys please I need some help in question 36 Nov 2008 paper 1 , why is it that chlorination couldn't remove the fertliliser? And question 13 in NOV 2009 paper 11, can anyone explain it please?
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The qystion 13's answer is D of course as at the cathode NaOH is produced which turns universal indicator blue(violet in real life) and at the anode chlorine is formed which after five minutes is completely diffused in air thus it is colourless at the positive electrode
 
To2a Bahaa

To2a Bahaa

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NKPyo said:
The qystion 13's answer is D of course as at the cathode NaOH is produced which turns universal indicator blue(violet in real life) and at the anode chlorine is formed which after five minutes is completely diffused in air thus it is colourless at the positive electrode
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Thanks a ton :) I have another question I'm sorry. If Sulphuric acid was the solution remaining in would be at the cathode?
 
To2a Bahaa

To2a Bahaa

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June 2000 paper 1 question 30, how can the acid have ph above 7?!?
and question 10 in the same paper. I really can't understand it.. PLEASE HELP! My exam is tomorrow
 
NKPyo

NKPyo

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To2a Bahaa said:
Thanks a ton :) I have another question I'm sorry. If Sulphuric acid was the solution remaining in would be at the cathode?
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Take electrolysis of dilute aqueous sodium sulphate for example:
sodium is formed at the cathode (and reacts with air to form sodium oxide immediately) and Oxygen is formed at the anode(and goes of gas)
Now what remains is just sulphuric acid.This can be taken out from either cathode after the reaction is done,but it would be preferred taking it out from the anode as there could be potential traces of sodium stuck to the tubes.
 
Shepard97

Shepard97

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Fatima18 said:
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w07_qp_1.pdf
Hey guys...number 33 is supposed to be D...however, isn't plating iron with zinc also a way of preventing rusting?
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Hmm .. I agree that the answer is D
The question says .. EASILY used for an Iron BRIDGE..
so you can't coat or grease a whole bridge!!
HENCE , the easiest method is painting :)
But yes all of the methods given are used to prevent rust... but it depends on the question.
 
F

Fatima18

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Shepard97 said:
Hmm .. I agree that the answer is D
The question says .. EASILY used for an Iron BRIDGE..
so you can't coat or grease a whole bridge!!
HENCE , the easiest method is painting :)
But yes all of the methods given are used to prevent rust... but it depends on the question.
Click to expand...
Is coating with grease also a method?If so, in which cases?
 
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