Physics, Chemistry and Biology: Post your doubts here!

[shafayat]

hey guys, do we need study organic chemistry for paper 6 !! please answer asap!!

no dude

 

[Dashexdan]

Anybody having good notes of polymerisation ?? i see all the p3's of chem have questions frm polymers =\

http://www.gcsescience.com/o55.htm

 

[sma786]

Explain why the combustion of waste crop material should not alter the percentage
of carbon dioxide in the atmosphere.

 

[sma786]

http://www.gcsescience.com/o55.htm

thanku ..!

 

[Dashexdan]

Explain why the combustion of waste crop material should not alter the percentage
of carbon dioxide in the atmosphere.

is that even there in our course??

 

[Dashexdan]

http://www.xtremepapers.com/community/threads/chemistry-revision.577/
hope it helps!

 

[sma786]

is that even there in our course??

i copied it from a past paper .. o/n 2010 ..

 

[Razzle-Dazzle]

Explain why the combustion of waste crop material should not alter the percentage
of carbon dioxide in the atmosphere.

Because the crops photosynthesized while they were alive, therefore the CO2 that goes into the atmosphere when they are burnt only cancels out the CO2 the crops took out via photosynthesis.

 

[mrnt3250]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s11_qp_62.pdf
Question 5, I totally get scared when I see this type of questions, and they always come.
I couldn't figure out whats the solid, etc.
So could you tell me what shall I study for this question? I have studied Testing for anions/cations (sulfate ions/carbonate ions/nitrate ions), Identifying gasses, Metal ions, etc..

 

[da7ee7_95]

Does anyone have any physics notes?

 

[Manobilly]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s11_qp_62.pdf
Question 5, I totally get scared when I see this type of questions, and they always come.
I couldn't figure out whats the solid, etc.
So could you tell me what shall I study for this question? I have studied Testing for anions/cations (sulfate ions/carbonate ions/nitrate ions), Identifying gasses, Metal ions, etc..

They have told above that the solid V is insoluble that means when the mixture is filtered it will be as a residue.
Than they have shown the tests on residue ,first is by lime water ,it turned milky that means its a carbonate and secondaly bu adding NaOH and ammonia ,with NaOH it gave a white precipitate which is insolube and with ammonia it gave no precipitate ,that means it is Calcium as calcium gives a slight or no precipitate with ammonia.

You have to remember the flame tests,the effect of adding ammonia and NaOH,the sulfate ions ,carbonates,chlorides.iodides,nitrates.And gases test for H2,Oxygen ,chlorine,ammonia and try remembering the litmus paper colors.

 

[Dashexdan]

Does anyone have any physics notes?

http://www.xtremepapers.com/community/threads/all-notes-o-level-0r-igcse-a-level.4866/ go to the physics portion!!

 

[Wasif`]

For CHEMISTRY PAPER 6 TO GET A*, STUDY :-
1. All the labeling and names of apparatus
2. Learn and revise CATION AND ANION again and again
3. Preparation of soluble salt, insoluble salt, titration and Precipitation method (step by step which gives examiner a good impression and sometimes bonus marks)
4.Reaction of Acid with basis , carbonate, salt
5. Learn pH scale by color and example of strong or weak acid
6. Chromatography, filtration, Crystallization, to separate solvent from solution by distillation, Fractional Distillation
7. Rate of Reaction and effect of increasing surface area, concentration, temperation, suitable catalytst and light
8. Photography by Silverbromide and Photosynthesis equations
9. Equilabrium and Energy change in reversible reaction
10. Solid, liquid and gasses states and properties.

GOOD LUCK EVERYONE

 

[mrnt3250]

There was a questions about appearance of some compounds lets say Potassium Iodide.
Since I haven't done much practicals, is there any list that contains useful paper 6 compound colors?

 

[da7ee7_95]

http://www.xtremepapers.com/community/threads/all-notes-o-level-0r-igcse-a-level.4866/ go to the physics portion!!

Thanks Mate!

 

[suhaib05]

Quick question: if I'm asked to write observations when excess aqueous sodium hydroxide is added to an iron (III) salt solution, should I say 'ppt. is insoluble in excess' or 'no change in excess'? The mark scheme of O/N 2003 says 'no change in excess'...

 

[sma786]

Quick question: if I'm asked to write observations when excess aqueous sodium hydroxide is added to an iron (III) salt solution, should I say 'ppt. is insoluble in excess' or 'no change in excess'? The mark scheme of O/N 2003 says 'no change in excess'...

better to write no change or insoluble in excess, =]

 

[sma786]

There was a questions about appearance of some compounds lets say Potassium Iodide.
Since I haven't done much practicals, is there any list that contains useful paper 6 compound colors?

http://boomeria.org/chemlectures/qual/qualnotes.pdf i think this might help try it .. if not, just temme =]

 

[sma786]

If anybody has any doubt in chemistry paper 6 , inbox me or tag me here,
Best of luck everybody =]

 

[ZainH]

If anybody has any doubt in chemistry paper 6 , inbox me or tag me here,
Best of luck everybody =]

I DO. Paper : http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_S08_qp_6.pdf
Question 5)f)

I wrote that it contains copper, but how can we tell it's an organic salt? (I'm very bad at chemistry, just saying :S )