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Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 356932 times)

Offline ~~~~shreyapril~~~~

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #105 on: November 07, 2009, 02:15:34 pm »
no it is tera bheja!!! :P :P
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nid404

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #106 on: November 07, 2009, 02:40:04 pm »
Quote from: ~~~~shreycool~~~~ on November 07, 2009, 02:15:34 pm
no it is tera bheja!!! :P :P

it could be tera bacha also.......sh*t im goin nuts......no EADA here plz..
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Offline ~~~~shreyapril~~~~

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #107 on: November 07, 2009, 02:54:49 pm »
age ka continued in EADA
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Offline @d!_†oX!©

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #108 on: November 10, 2009, 12:47:35 pm »
hey guys what's the definition of relative atomic mass??
don't explain it, cuz i already know what it means but what will be its precise definition for a 1 or 2 mark question??
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Offline Ghost Of Highbury

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #109 on: November 10, 2009, 01:42:43 pm »
the mass of an atom on a scale where an arom of C-12 weighs exactly 12 units.
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Offline @d!_†oX!©

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #110 on: November 10, 2009, 01:53:58 pm »
ohhkk Thanks aadi....and relative molecular mass??
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Offline Ghost Of Highbury

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #111 on: November 10, 2009, 01:55:28 pm »
the sum of relative atomic masses of all atoms in a molecule.
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Offline @d!_†oX!©

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #112 on: November 10, 2009, 01:56:31 pm »
tyvm again!! :)
done with add. maths??
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Offline @d!_†oX!©

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #113 on: November 10, 2009, 02:01:50 pm »
another one:
Which of them is endothermic ?
a)The formation of a hydrogen-chlorine bond
b)The formation of rust
c)The formation of water from ice
d)The formation of water from oxygen and hydrogen
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Offline Ghost Of Highbury

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #114 on: November 10, 2009, 02:07:01 pm »
it shud b C

a) forming bonds -exo
b) reacts with oxygen, maybe exo
d) ofcourse exo.
for ice--> water, it has to melted i.e suply energy, and energy is taken in
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Offline @d!_†oX!©

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #115 on: November 10, 2009, 02:10:26 pm »
Even i think it should be C
thanks aadi
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nid404

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #116 on: November 10, 2009, 02:21:31 pm »
yes ofc it's C
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Offline @d!_†oX!©

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #117 on: November 10, 2009, 02:55:03 pm »
ok people..here i am again...

Tungsten metal, W, is manufactured by reducing tungsten(III)oxide, WO3, whit carbon.

WO3 + 3C -----> 3CO + W

Calculate the mass of carbon needed to reduce 116g of tungsten(III)oxide.

-------------------------------------------------------------------------------------------------------------------------------
Now, I know how to do it.
We first take out the number of moles of WO3
which comes out to be 116/232 = 0.5 moles
Then, as the ratio is 1:3
Thus, the number of moles of C = 0.5*3 = 1.5 moles
Thus, the mass of carbon = 1.5*12 = 18g

Now my question,
if the ratio according to the equation is 1:3 for WO3:C
The how is it possible that for 116g of WO3 only 18g of C is required?

So, i thought maybe i have done it wrong although this is the correct method itself, but i still tried
Having the mass of WO3 as 116g and the ratio being 1:3
thus, the mass of C be 3*116 = 348g

But, the second method is wrong, isn't it?
then how are we getting 18g as the mass of Carbon required??

Please help guys!!!
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Offline Ghost Of Highbury

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #118 on: November 10, 2009, 03:02:02 pm »
wats the answer?
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Offline @d!_†oX!©

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Re: ~~~All Chemistry Doubts Here~~~
« Reply #119 on: November 10, 2009, 03:03:12 pm »
That's the problem dude...i don't have the answer...... :-[
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