Physics, Chemistry and Biology: Post your doubts here!

[kainat husain]

2bv: As increasing the temperature would favour the backward reaction which would reduce the yeild
3ciii: powdered catalyst is used so it will be faster i.e more higher/steeper and the volume of nitrogen will not be effected so it will end at the same point
6ai: open the double bond of the monomer to both sides and put square brackets around it

thanx

 

[sma786]

i find this topic the easiest

i find it the worst topic of chem

 

[za Shadow]

y u want help?? isn't paper 3 already over??

Paper 3 is over.

soooooooooooooooooooooooooooooo sorry guys i meant p3 chemistry sorrryyy my bad
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_qp_33.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_ms_33.pdf
Q 5 b ii) plzzz help why all 0.2
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_qp_32.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_ma_32.pdf
1 d) why F why not C ????????
sryyy again

 

[thats_me]

k thanks
how cm ur so perfect in stroicheometry? any trick or tip ?

Actually cz ive practiced alot of it, i used hate it before :| but now that ive done most of the pastppr ques i kinda got the concept

 

[sma786]

anybody has good notes for polymerisation ..?

 

[thats_me]

soooooooooooooooooooooooooooooo sorry guys i meant p3 chemistry sorrryyy my bad
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_qp_33.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_ms_33.pdf
Q 5 b ii) plzzz help why all 0.2
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_qp_32.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_ma_32.pdf
1 d) why F why not C ????????
sryyy again

LOL!

 

[moon angel]

heey everyone, does anyone of you know a website for the marking scheme for 1993 .... chemistry past papers ??
thnxx and good luck

 

[ZainH]

heey everyone, does anyone of you know a website for the marking scheme for 1993 .... chemistry past papers ??
thnxx and good luck

1993!??! What the hell are you doing solving past papers from 1993? I didn't even know they existed..
Syllabus was MUCH MORE different back then lol.. start solving from around 2006.

 

[thats_me]

soooooooooooooooooooooooooooooo sorry guys i meant p3 chemistry sorrryyy my bad
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_qp_33.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_ms_33.pdf
Q 5 b ii) plzzz help why all 0.2
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_qp_32.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_ma_32.pdf
1 d) why F why not C ????????
sryyy again

5: no of moles=mass/molar mass
the mass of C=2.4 ,H=0.2 ,O=3.2 (frm question)
molar mass of C=12 , H=1 ,O=16 (frm periodic table)
so C=2.4 /12=0.2
H=0.2/1=0.2
O=3.2/16=0.2

1: because sodium chloride is an ionic salt it conducts electricity in liquid

 

[moon angel]

1993!??! What the hell are you doing solving past papers from 1993? I didn't even know they existed..
Syllabus was MUCH MORE different back then lol.. start solving from around 2006.

i heard that questions will be like 1993 and 1994 ( before 2000) so what are u loosing

 

[sma786]

i heard that questions will be like 1993 and 1994 ( before 2000) so what are u loosing

i wasnt even born back then

 

[za Shadow]

5: no of moles=mass/molar mass
the mass of C=2.4 ,H=0.2 ,O=3.2 (frm question)
molar mass of C=12 , H=1 ,O=16 (frm periodic table)
so C=2.4 /12=0.2
H=0.2/1=0.2
O=3.2/16=0.2

1: because sodium chloride is an ionic salt it conducts electricity in liquid

Thanks 4 number 5
but number 1, C conducts electricity when liquid and doesn't in solid.... and also it has a high melting and boiling point and this is a property in the ionic compounds but F has a very low mp and bp it is not an ionic comp for sure don't u think??????

 

[moon angel]

n

i wasnt even born back then

neither me

 

[thats_me]

Thanks 4 number 5
but number 1, C conducts electricity when liquid and doesn't in solid.... and also it has a high melting and boiling point and this is a property in the ionic compounds but F has a very low mp and bp it is not an ionic comp for sure don't u think??????

Oopps!! extremely sorry i din c the ques properly i saw d instead of c
i guess thats because it says AQUEOUS sodium chloride which is liquid at room temp so the mp should be below room temp the next says ionic compound which is C

 

[za Shadow]

Oopps!! extremely sorry i din c the ques properly i saw d instead of c
i guess thats because it says AQUEOUS sodium chloride which is liquid at room temp so the mp should be below room temp the next says ionic compound which is C

THANKS A LOOOOOT

 

[thats_me]

THANKS A LOOOOOT

anytime

 

[AAnsarii]

Guys when we add potassium manganate (vii) to a solution, they sometimes ask what is observed?
Can we just say the color changes from purple to colorless?

solution of what?

 

[AAnsarii]

Fe2O3 + CO ==> Fe + CO2
how do v balance dis?

 

[EpicLol]

Could anyone help with this: Chemistry paper 3 November 2004
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w04_qp_3.pdf

Question 8 (a) (i) [the table]

I know the first box is C6H12
I am asking about the boiling point, I'd like to know how to get it, and also how to predict any boiling point in any question not just this one, whether there's a method or something to get it.

Thanks in Advance.

If u look at the rest of the boiling points u can see a pattern...41 37 and then it could be 33....ignoring the first one....
The only way u can answer these kinda questions is by finding a pattern kind of....

 

[EpicLol]

Fe2O3 + CO ==> Fe + CO2
how do v balance dis?

Fe2O3 + CO ==> 2Fe + CO2

thats as simple as adding a 2 infront of Fe