Physics, Chemistry and Biology: Post your doubts here!

[asma tareen]

but they say it is dissolved in a diluted solution of H2SO4 , which when reacting with zinc oxide, produces both zinc sulfate and water, therefore water is present , and H2 must be discharged.

look molten zinc salt will be used ok it can be zinc chloride and when a compound is melted its in liquid state so no need to disslove in water

 

[Henry Smith]

An important chemistry problem !!!!
in extraction of zinc , they say it can be done by both ; reduction by carbon or electrolysis.
but in electrolysis, hydrogen is less reactive than zinc , so it is the one who is supposed to be discharged, instead, they say that zinc is deposited at the cathode.
can somebody help me please because this is so confusing??!!
thanks.

The two commercial methods of reducing ZnO to Zn appear to be
Thermal, in the presence of C:
2 ZnO + C → 2 Zn + CO2
and electrowinning:
ZnO + H2SO4 → ZnSO4 + H2O (followed by electrolysis on the ZnSO4)

Today over 90% zinc is produced hydrometallurgically in electrolytic plants.

Check this out : http://www.zinc.org/basics/zinc_production

 

[asma tareen]

then they would have extracted the zinc sulphate and melted it probably

 

[rome mate]

pls explain how the equilibrium favor right side and left side...................pls help​

 

[Sam Ivashkov]

its just the point where they intersect.. which is 22.5

alright. Thank you!

 

[Henry Smith]

No problem! just wanted to ensure ppl dont get confused lol.. and thats really helpful for the boy! insA he will do well!

Hi Raven,

Could you please check this p61_may_2012 for me as well, point out the mistakes and I will amend them. Thanks in advance!

Another paper for you Maria!

Link to the paper : https://www.yousendit.com/download/UVJnY05xZy9ubVZESjlVag

 

[Princess Raven]

guys do amphibians have internal or external ears?

 

[Princess Raven]

Hi Raven,

Could you please check this p61_may_2012 for me as well, point out the mistakes and I will amend them. Thanks in advance!

Another paper for you Maria!

Link to the paper : https://www.yousendit.com/download/UVJnY05xZy9ubVZESjlVag

ill check it out

 

[Princess Raven]

Hi Raven,

Could you please check this p61_may_2012 for me as well, point out the mistakes and I will amend them. Thanks in advance!

Another paper for you Maria!

Link to the paper : https://www.yousendit.com/download/UVJnY05xZy9ubVZESjlVag

q 4 part f is wrong.. they will have the same height because the solution is saturated and can dissolve no more solute.. and part e is correct but would u mind explaining it to me.. i dont get it.. everything else is correct except the table entry but yes u had mentioned it was according to the printout obtained

 

[CaptainOmerica]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_qp_61.pdf
in the first question which one is ethanol and which one is aluminium oxide??

The label on the Cotton wool is Ethanol and the label on the stuff in the center of the test tube is Aluminium Oxide(it's the catalyst just so you)...

 

[CaptainOmerica]

i

btw why did u start from 60? why not 10? and paper 62 oct/nov 2010 question 3b the graph, could u solve it and upload
and the ray diagram in paper 2010 may/june 61 please solve and upload . thanks

I am terribly sorry for the late reply. I don't use this site that much. xD Now I don't know when you might get this. But hey, always down for the help. xD I started from 60 because that's the appropriate starting for the units, starting from 10 wouldn't fit my scale. And since we don't have to include the origin, make the most of it!
I'll try to solve the other questions you sent too. BTW do you take Biology? If yes, help me out please, I'm hopeless.

 

[CaveDweller65]

Physics. Q.1 (a) (b) (c) (d) Explain it Please!!!! Ohh.. btw in part (a) i just need resultant..plz explain
http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_w10_qp_31.pdf

 

[sarmad12]

ANYONE GOT SOME GOOD NOTES FOR BIOLOGY. I AM REALLY A GONER IN BIO AND THERE IS NO TIME LEFT. PLEASE DONT IGNORE.

 

[Henry Smith]

q 4 part f is wrong.. they will have the same height because the solution is saturated and can dissolve no more solute.. and part e is correct but would u mind explaining it to me.. i dont get it.. everything else is correct except the table entry but yes u had mentioned it was according to the printout obtained

Hi Raven,I've corrected what you pointed out, just missing the word "height". Actually, PbCl2 is insoluble that is why the precipitate deposits on the bottom of the test tube, lead nitrate ran out so further tubes should have the same height of solids in them.

The number entry was measured by a ruler on my screen, I know that the MS says something different to mine. Of course when they hand the papers out, they should be printed as 1:1 scale i think.

Here is my amended version for the previous paper you pointed the mistake out. Grateful Raven!

https://www.yousendit.com/download/UVJnY05qQzdVVG52bk1UQw

 

[sweetiepie]

https://www.xtremepapers.com/community/threads/useful-stuff-compiled.10273/ Notes Added Check Out Hope This Helps

 

[skiko troller]

can someone tell me how to study for chemistry/bio paper 6

 

[fatimanasir]

i
I am terribly sorry for the late reply. I don't use this site that much. xD Now I don't know when you might get this. But hey, always down for the help. xD I started from 60 because that's the appropriate starting for the units, starting from 10 wouldn't fit my scale. And since we don't have to include the origin, make the most of it!
I'll try to solve the other questions you sent too. BTW do you take Biology? If yes, help me out please, I'm hopeless.

I do take biology
amazing notes for biology attached

 

[fatimanasir]

Bio important notes attached

 

[Masroor Hussain]

Need Help Physics:
http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_w10_qp_32.pdf
I'm getting the wrong answer for question 2(b)(ii). I Think the height is 0.2 m but the ms say's it's 0.1, why is it 0.1 m not 0.2.

 

[CaptainOmerica]

I do take biology
amazing notes for biology attached

SERIOUSLY. THANK YOU SO MUCH! IN DEBT! x"D (Y)