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Author Topic: Chemistry AS Multi Choice Help  (Read 9785 times)

Offline happy angel

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Re: Chemistry AS Multi Choice Help
« Reply #15 on: November 18, 2009, 11:35:00 am »
Hard water contains calcium ions and hydrogencarbonate ions arising from dissolved calcium
hydrogencarbonate, Ca(HCO3)2.
How many electrons are present in the hydrogencarbonate anion?
A 30 B 31 C 32 D 33

The answer is C.. can sm1 xplain to me the answer plzz?
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Offline MaNi_DaDuDe

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Re: Chemistry AS Multi Choice Help
« Reply #16 on: November 18, 2009, 11:44:17 am »
Quote from: happy angel on November 18, 2009, 11:35:00 am
Hard water contains calcium ions and hydrogencarbonate ions arising from dissolved calcium
hydrogencarbonate, Ca(HCO3)2.
How many electrons are present in the hydrogencarbonate anion?
A 30 B 31 C 32 D 33

The answer is C.. can sm1 xplain to me the answer plzz?

1stly,

# Protons = # Electrons

H = 1
C = 6
O = 8x3 = 24
 Total = 24+6+1 = 31

HCO3- means it has a negative charge on it. So, it has gained an electron.

Thus, 31+1 = 32 electrons.

:)
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Offline MaNi_DaDuDe

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Re: Chemistry AS Multi Choice Help
« Reply #17 on: November 18, 2009, 11:48:18 am »
Quote from: kratos009 on November 18, 2009, 11:19:26 am
Wow thanks a lot Mani, there are heaps of questions  ;D.

+rep. You better get back to studying  :P.

You better start* studying. < lol

Thanks.

I'll see if I can scan and upload a few more topics later. :]

I was just frustrated as my Adobe PDF converter was giving errors; for no reason.  >:(

gl.
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Offline happy angel

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Re: Chemistry AS Multi Choice Help
« Reply #18 on: November 18, 2009, 12:47:06 pm »
Quote from: MaNi_DaDuDe on November 18, 2009, 11:44:17 am
1stly,

# Protons = # Electrons

H = 1
C = 6
O = 8x3 = 24
 Total = 24+6+1 = 31

HCO3- means it has a negative charge on it. So, it has gained an electron.

Thus, 31+1 = 32 electrons.

:)

ah okiie.. thanx dude!!! :-* :)
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Offline MaNi_DaDuDe

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Re: Chemistry AS Multi Choice Help
« Reply #19 on: November 18, 2009, 12:53:34 pm »
Quote from: happy angel on November 18, 2009, 12:47:06 pm
ah okiie.. thanx dude!!! :-* :)

Your very welcome. :]
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Offline 123

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Re: Chemistry AS Multi Choice Help
« Reply #20 on: November 18, 2009, 01:12:08 pm »
Quote from: MaNi_DaDuDe on November 18, 2009, 11:15:23 am
Well, I scanned this book and it has old paper questions as well.. with the answers, etc.

I hope it helps. Took me hours scanning. It still won't convert to PDF.  >:( >:( >:( >:( !@#$

Anywho, it has Introduction to Organic Chemistry, Hydrocarbons and Polymerisation.
It does not include carboxylic acids, carbonyl compounds, and hydrogen derivatives. (I was too tired to scan more, plus I haven't started studying at all..so yeah)

Mainly for Vince, but if others benefit too = :D

+rep, if it helped you.

Good Luck for the exam guys!

pz

-MaNi
OMG...Mani...dude ur da best... THANKU FOR UR EFFORT
Is this a book?? If so then isn't there a ebook for it?? I tried searching for a ebook & got this: http://nowdownloadall.com/your-file.asp?pb=4&PID=92d75e3c-6ff7-408e-8a60-6c1abcebcf98&q=gce%20a%20level%20chemistry%20mcq%20with%20helps
But the damn thing asks for payment...i hate these types of download site they advertise everythin is free but in Step 2 suprise suprise!! Any1 know how to get past this & just download that ...helps book??

Any ways...i'm sure atleast 5 questions will come from that helps...book...where is this book from- I don't think CIE is gonna b kind enough to compile such a book!  :P
Mani...please do upload the other parts of organics....also if possible the inorganics too!  :o

PS: ur scanner software should have scan as pdf or document option...that way it scans into a pdf...thats how mine is like! otherwise go print on the .doc file & select printer as Adobe PDF...that saves the entire .doc as .pdf....  I have Adobe acrobat pro 7; Do u?? Maybe that gives  u these features .=P
« Last Edit: November 18, 2009, 01:17:15 pm by 123 »
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Offline MaNi_DaDuDe

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Re: Chemistry AS Multi Choice Help
« Reply #21 on: November 18, 2009, 01:24:36 pm »
It's a singaporian book. No, i couldn't find it online (I searched for days). I got it shipped.

I know how to convert to a PDF, lol. Just an error here and there. So it would halt activity after converting a few pages.

I'll try uploading a few more organic once I have started studying myself. I've been wasting time all day. lol.

You're welcome. :)

Hope it helps.
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Offline AndrewCedric

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Re: Chemistry AS Multi Choice Help
« Reply #22 on: November 18, 2009, 03:18:08 pm »
Thx forr the attachment MAniiiiiiiiiii... By the way, do you think that P1 is kinda difficult to score A???
I think that we need to read more.. Those are general chemistry that sometimes its not even in the book.. Except for the organic part..
And the frustrating 10 last questions..

Lastly, Any thread discussing Chem P2???
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Offline josephwhite

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Re: Chemistry AS Multi Choice Help
« Reply #23 on: November 18, 2009, 04:05:06 pm »
Yea, the frustating final 10, with more than 1 answer is correct.
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Offline MaNi_DaDuDe

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Re: Chemistry AS Multi Choice Help
« Reply #24 on: November 18, 2009, 05:04:18 pm »
Quote from: AndrewCedric on November 18, 2009, 03:18:08 pm
Thx forr the attachment MAniiiiiiiiiii... By the way, do you think that P1 is kinda difficult to score A???
I think that we need to read more.. Those are general chemistry that sometimes its not even in the book.. Except for the organic part..
And the frustrating 10 last questions..

Lastly, Any thread discussing Chem P2???

I think the last 10 are the worst :D
You write an answer, scribble it out, write another, scribble, then finally just do inny minny miny mo. :/ Quite frustrating.

Chem p2, I'm sure there was one. Look in subject doubts. Else, I'll find it when I get on a PC.
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Offline lonelyboy

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Re: Chemistry AS Multi Choice Help
« Reply #25 on: November 18, 2009, 08:29:49 pm »
Best of luck guys! Kill it.


 :D
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Offline MaNi_DaDuDe

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Re: Chemistry AS Multi Choice Help
« Reply #26 on: November 18, 2009, 11:09:09 pm »

Does anyone know the uses of certain chemical compounds?

They asked something about a bromo-halogenoalkane which was used as a fire extuingisher or something in May/June.
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Offline vince_24

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Re: Chemistry AS Multi Choice Help
« Reply #27 on: November 18, 2009, 11:24:54 pm »
Heres the PDF Version of what MaNi posted. A lot of chemistry multi choice questions, etc. Very helpful

http://www.megaupload.com/?d=7CBYEBYX

Enjoy.
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Offline MaNi_DaDuDe

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Re: Chemistry AS Multi Choice Help
« Reply #28 on: November 18, 2009, 11:39:15 pm »
Quote from: vince_24 on November 18, 2009, 11:24:54 pm
Heres the PDF Version of what MaNi posted. A lot of chemistry multi choice questions, etc. Very helpful

http://www.megaupload.com/?d=7CBYEBYX

Enjoy.

Thanks a lot bro. :)

+rep'd.
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Offline happy angel

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Re: Chemistry AS Multi Choice Help
« Reply #29 on: November 19, 2009, 04:11:16 am »
Use of the Data Booklet is relevant to this question.

Ethyl ethanoate can be obtained from ethanoic acid and ethanol by the following reaction.

CH3CH2OH + CH3CO2H--> CH3CO2CH2CH3 + H2O

Ethanol (30 g) and ethanoic acid (30 g) are heated under reflux together, and 22 g of ethyl
ethanoate are obtained.

What is the yield of the ester?
A 25 % B 38 % C 50 % D 77 %

the answer is C.. how???
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