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Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 357675 times)

Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2115 on: May 24, 2010, 09:34:07 pm »
Quote from: deadman786 on May 24, 2010, 09:28:51 pm
That happens at your place too??? HAHAHAHA lol. Our teacher tried to be extra clever so he mixed nov 09 gce with igcse nov 09. HAHAH but we had already LEARNED all the answers in both of em' :D. 90% of the class got 40 :D.

LOL not only for paper 1 but for all chem papers  .. so our sir kept the boundary as 95% for A* in mock :P but most of us got abv 90%
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Offline the_grim_reaper

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2116 on: May 24, 2010, 09:38:49 pm »
Quote from: ~VIN1094~ on May 24, 2010, 09:34:07 pm
LOL not only for paper 1 but for all chem papers  .. so our sir kept the boundary as 95% for A* in mock :P but most of us got abv 90%


Man for us it was nov 09 (all papers) in Physics and Chemistry!!!! LOL Bio was MOSTLY gce nov 09. Maths and English weren't from past papers..

In our school, 90% for A* is fixed so our teacher then decided to cut marks for odd things lol :D.
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Offline 7ooD

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2117 on: May 24, 2010, 09:48:38 pm »
oooh thanks 1 more plz in question 8 same exam it says element v forms an acidic covalent oxide which row in the table shows how many electrons there could be in the outer shell of an atom of v (1 2 6 7 ) in ms they choose 6 and 7 why
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Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2118 on: May 24, 2010, 09:54:30 pm »
Quote from: 7ood on May 24, 2010, 09:48:38 pm
oooh thanks 1 more plz in question 8 same exam it says element v forms an acidic covalent oxide which row in the table shows how many electrons there could be in the outer shell of an atom of v (1 2 6 7 ) in ms they choose 6 and 7 why

ok listen .. always ..

acidic oxide is a non-metal ..

also covalent means involving a non-metal ..

ALL non-metals have a valency starting from 4, 5, 6, 7 .. because they need to gain electrons .. u may find this in the "Periodic Table" chapter in your book .. if it has .. consider revising it .. ;) got it ??
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Offline Shazizzzle

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2119 on: May 24, 2010, 09:59:05 pm »
Quote from: A@di on May 24, 2010, 09:27:59 pm
-All Chlorides, bromides and iodides are soluble except lead chloride/bromide/iodide, silver Cl/Br/I, and mercury Cl/Br/I

-All sulphates are soluble except lead sulphate, barium sulphate and calcium sulphate

-All carbonates are insoluble except Sodium, potassium (All group 1 metals in general) and ammonium carbonates, which are soluble.

-All hydroxides are insoluble except Sodium, potassium(All group 1 metals in general), ammonium, calcium, strontium and barium hydroxides, which are soluble.

-All nitrates are soluble


heres the list



MINE! :P (c) !
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Offline 7ooD

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2120 on: May 24, 2010, 10:12:41 pm »
thanks mate u r the best :D
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Offline the_grim_reaper

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2121 on: May 24, 2010, 10:13:08 pm »
hahahahahahha Shaz be generous!!! So you're finally online! (I was wondering where you were)!!!
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Offline the_grim_reaper

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2122 on: May 24, 2010, 10:15:03 pm »
YAAAAAAAAA!!!!!!!!!!!!!!!!!!!!! I'm not a newbie any more!!! (By the way how did that change?? It's not like I'm helping a lot of people. Infact I'm troubling them :D.)
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Offline NidZ- Hero

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2123 on: May 24, 2010, 10:15:24 pm »
can u plz explain y this thank u any1
 :)
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Offline NidZ- Hero

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2124 on: May 24, 2010, 10:18:19 pm »
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Offline Shazizzzle

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2125 on: May 24, 2010, 10:20:34 pm »
Quote from: Nidzzz on May 24, 2010, 10:15:24 pm
can u plz explain y this thank u any1
 :)

The answer is C.

This is because, the air in the jar contains, along with all the other components in the air, OXYGEN. This OXYGEN, i.e 21% is USED UP by the iron fillings as they react with it to form iron oxide, i.e rust, which is also hydrated.

As the oxygen is used up, water in the tube rises to replace the lost volume of the oxygen.
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Offline Ivo

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2126 on: May 24, 2010, 10:20:50 pm »
Can someone explain Q4, 22 of w08 paper 1, thanks
« Last Edit: May 24, 2010, 10:23:53 pm by Ivo »
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"In helping others, we shall help ourselves, for whatever good we give out completes the circle and comes back to us."

Offline Vin

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2127 on: May 24, 2010, 10:22:19 pm »
Quote from: deadman786 on May 24, 2010, 10:15:03 pm
YAAAAAAAAA!!!!!!!!!!!!!!!!!!!!! I'm not a newbie any more!!! (By the way how did that change?? It's not like I'm helping a lot of people. Infact I'm troubling them :D.)

number of posts ..  ;)
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Offline NidZ- Hero

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2128 on: May 24, 2010, 10:22:56 pm »
Quote from: Shazizzzle on May 24, 2010, 10:20:34 pm
The answer is C.

This is because, the air in the jar contains, along with all the other components in the air, OXYGEN. This OXYGEN, i.e 21% is USED UP by the iron fillings as they react with it to form iron oxide, i.e rust, which is also hydrated.

As the oxygen is used up, water in the tube rises to replace the lost volume of the oxygen.
hey shazii can u plz tell de equation of rusting
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Offline NidZ- Hero

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Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #2129 on: May 24, 2010, 10:24:44 pm »
explain plz i m sry i m realli dumb
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