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Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 333143 times)

Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #570 on: May 07, 2010, 04:48:05 pm »
Quote from: the golden girl on May 07, 2010, 04:29:05 pm
okay i'll give u all the questions that i have doubt in that r related to oxides ,k ? ....but plz do explain cuz i kno what the answers r cuz of the ms ..,k?

well herei  go :

jun2001 question 14)
nov 2001 question 21)
nov 2003 q 16) ..19) and 26)
jun 2004 q 9)..14)..26)
nov q 11)


i kno that's alot .....well my bro is pain in the neck .hence i'll sign out right  now ...but i'll be back abd 2 hours later or smthn ..... and i really would apprectiate it if u would have answered me by then ...


thx alot !!!

june 04

9) A ..has to be only one showing a correct formula for lead(II)Nitrate!! Pb(NO3)2
14)  D ..hydrogen in a fuel always combines with air
26)  A .. z least reactive as it occurs naturally as the metal

nov 04
11)  A  ..copper oxidizes when heated in air

will take time to ans others havta hav my dinner!..:)
« Last Edit: May 07, 2010, 04:51:16 pm by ~VIN1094~ »
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Offline Ghost Of Highbury

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #571 on: May 07, 2010, 05:07:14 pm »
june 2001 q14 - C. the gas released is obviously hydrogen because the metal will displace hydrogen from steam. steam is reduced because the H has gained an electron.

nov 2001 - 21 - A. Calcium oxide + HCl --> Calcium chloride + water. litmus red (acid) to blue (excess CaO)

nov 2003 - 16) B, lead oxide is reduced, lead remains, H20 (steam) dries up and adds to the drying agent.
                19) C, neutralization because of acid + base. filtration at last.
                26) B, hydrogen will displace copper.

june 04 -    9 - A, perfectly balanced

                14) D - combustion

         26) A. electrolyzing is used for very reactive metals. unreactive metals occur naturally
« Last Edit: May 07, 2010, 05:25:23 pm by A@di »
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #572 on: May 07, 2010, 05:19:40 pm »
nov 03

16) B .. lead oxide is decomposed hence mass decreases and O2 is displaced on the right so ova there mass inc.

19) C .. MgSO4 is a salt formed by reacting a base and an acid, they neutralize to form a salt thn the solution has to be filtered to seperate

26) B .. only copper can be displaced by Hydrogen..study reactivity series..

i feel these are too easy..im happy.. evn i had a lot of probs solvin such ques ..:)

  
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Offline The Golden Girl =D

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #573 on: May 07, 2010, 07:13:43 pm »
thx alot , both of u !! ....... i feel like i awe u alot .....really thx alot !!

~VIN1094~ - i  just want to know how did u get to feel they're  too easy ..in other words , what did u do to feel so not worried/so comfortable with chemistry paper 1 or even such questions?...

thx in advance
« Last Edit: May 07, 2010, 07:19:33 pm by the golden girl »
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Offline Ghost Of Highbury

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #574 on: May 07, 2010, 07:19:24 pm »
Quote from: the golden girl on May 07, 2010, 07:13:43 pm
thx alot , both of u !! ....... i feel like i awe u alot .....really thx alot !!

~VIN1094~ - i  just wanna kno how did u get ot feel there too easy ..in other words , what did u do to feel so not worried/so comfortable with chemistrey paper1 or even such question?...

thx in advance

ur welcome
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #575 on: May 07, 2010, 07:27:47 pm »
Quote from: the golden girl on May 07, 2010, 07:13:43 pm
thx alot , both of u !! ....... i feel like i awe u alot .....really thx alot !!

~VIN1094~ - i  just wanna kno how did u get ot feel there too easy ..in other words , what did u do to feel so not worried/so comfortable with chemistrey paper1 or even such question?...

thx in advance
ur welcome
its all practice which made me confidant .. if i had to say jus kno ur concepts well .. the thing is chemistry paper 1 wasn't too easy until a month ago but as u might kno im preparing fo boards now n obvi i might hav studied chemistry ..

but i lack miserably in stoichiometry .. i cant even spell it properly !! :p

i'd recommend u study from "complete igcse by RoseMarie Gallaghar and Paul Ingram" .. an amazing book gets all your doubts cleared !! :)
if u dont hav it u might consider visiting ur school library .. its still not late :)
in fact complete is good for all 3 sciences ..

gud luck !! :)   (guess wat this is my 100th lucky post .. :P)
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Offline CatAly$t

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #576 on: May 07, 2010, 08:17:30 pm »
can somebody tell me what's the difference between ester link and amide link???
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #577 on: May 07, 2010, 08:49:33 pm »
Quote from: CatAly$t on May 07, 2010, 08:17:30 pm
can somebody tell me what's the difference between ester link and amide link???

Esters are basically umm.. when u react alcohols with carboxylic acids u get esters ..
say ..
propanoic acid  +  butanol   <===>  butylepropanoate

they are reversible ..   (pls. dont go over my spellings, another thing im concerned about my exams)

amide link is where a couple of monomers have joined .. im sorry i dont have any means to show you in a graphical way .. :(
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nid404

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #578 on: May 07, 2010, 09:01:36 pm »
amide link or peptide link is formed when the amine group of one monomer reacts with the carboxylic acid of another in a condensation polymerisation reaction...

               O
               ||
NH2 -(R1) -C-N- (R2)-COOH
                   |
                   H

the CONH bond is the amide link.  R1 and R2 represent different monomer units(amino acids). By product of this reaction is water
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #579 on: May 07, 2010, 09:10:51 pm »

hmm Thanks ..  :)
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Offline CatAly$t

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #580 on: May 07, 2010, 09:43:59 pm »
Quote from: nid404 on May 07, 2010, 09:01:36 pm
amide link or peptide link is formed when the amine group of one monomer reacts with the carboxylic acid of another in a condensation polymerisation reaction...

               O
               ||
NH2 -(R1) -C-N- (R2)-COOH
                   |
                   H

the CONH bond is the amide link.  R1 and R2 represent different monomer units(amino acids). By product of this reaction is water
thanks...can u tell me what is ester link?ur explanation is easy to understand  ;D
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Offline Baladya

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #581 on: May 07, 2010, 10:08:07 pm »
C-C=O                                                                                            O 
     |                       +             OH-C-C              =                           ||
                                                                                                    C-C  -  O - C-C
    OH
(Ethanoic Acid)               (Ethanol)                                    (Ethyle Ehanoate )
                                                                                            The ester Link is the:
                                                                                                        (    O        )
                                                                                                        (   ||        )
                                                                                                        (    C - 0  )
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Offline Ghost Of Highbury

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #582 on: May 08, 2010, 05:27:09 am »
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nid404

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #583 on: May 08, 2010, 09:19:33 am »
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Offline CatAly$t

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #584 on: May 08, 2010, 01:41:27 pm »
thanks guys for everything!! :D
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