smith50
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#1161
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#1161
(Original post by amish123)
Right first work out the total mass change if one uranium atom disintegrates,

so 390.406 + 1.675 - (149.357 + 239.056 + 2x1.675)

and you get a mass difference of 3.18 x 10^-27kg.

Now, for a uranium atom, there are 235g per mole. So if you want to find the mass change for 0.5kg, you do 500/235 x (6.0 x 10^23) and this will give you the number of uranium atoms in 0.5kg. You'll get an answer of 1.276 x 10^24 atoms.

Then you just multiply the mass difference if one uranium atom disintegrates by the number of uranium atoms you have, so (3.18 x 10^-27) x (1.276 x 10^24) and you'll get a final answer of 4.06 x 10^-4kg, or 406g.

Hope that helps!
But the mass difference you get 0.318^-27kg:confused:
Also what is argon dating ?
Thanks,
Smith
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Thr33
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#1162
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#1162
(Original post by iwantopas19)
hahaha omg..I wrote kekule lol.. i hate chem...my worst nightmare.
I really felt like the paper was really really easy for anyone who understands chemistry (im not included)
Yeah, my hatred of Chemistry has grown sooooo much over the past couple of months. Admittedly, the paper did give out a lot of marks for really standard stuff - more of a memory test than anything. As I say though, a few tricky things that'll probably even out the scores.
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fwook
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#1163
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#1163
Anyone else got M2 on Friday but been focussing all their efforts on Physics, or is it just me?
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Caramelapps
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#1164
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#1164
Can anyone help me with Question 3.b)I) Section A (nuclear bit) of the June 2012 paper. Markscheme isn't helping me :-/ and cant get the right answer.
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Allahu Akbar
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#1165
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#1165
(Original post by Thr33)
Yeah, my hatred of Chemistry has grown sooooo much over the past couple of months. Admittedly, the paper did give out a lot of marks for really standard stuff - more of a memory test than anything. As I say though, a few tricky things that'll probably even out the scores.
Very sneaky :sneakydevil: I thought we had to leave it a day for edexcel chemistry
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OmegaKaos
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#1166
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#1166
(Original post by Caramelapps)
Can anyone help me with Question 3.b)I) Section A (nuclear bit) of the June 2012 paper. Markscheme isn't helping me :-/ and cant get the right answer.
Its just knowing that gamma is emitted in all directions.
they tell you the area is 1.5*10^-3
But it spreads out inn relation to 4Pi*r^2(r=0,1.8)

so 1.5*10^-3/4Pi*(0.18)^2 = 3.68*10^-3
thats approx 4*10^-3
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Thr33
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#1167
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#1167
(Original post by Allahu Akbar)
Very sneaky :sneakydevil: I thought we had to leave it a day for edexcel chemistry
Woops...I avoid the Chem forums like the plague and it's my only edexcel exam :evilbanana:
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sports_crazy
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#1168
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#1168
Astrophysics. Is there a difference between black body temperature in Wiens law and the temperature in Stefans law. I mean are this both surface temperature.
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laser174572
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#1169
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#1169
(Original post by smith50)
It was a 2 marker .Anyways I'm glad you get it now
Could you help me out on this question please Attachment 226564
Thanks,
Smith
Out of interest, what paper/book is that question from?


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michael13
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#1170
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#1170
(Original post by HEH95)
done all 3 of the recent papers (june 10,11,12)

Was going to start looking at old spec papers for a bit this afternoon...can anyone confirm if this is worth doing?
ie. has the specification changed that much between june 09/june 10 ??
I found it helpful to solve some of the old papers as the specifications are almost identical.
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Matt III
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#1171
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#1171
This may have already been posted, but in the mark schemes for the mathsy questions they always seem to give one answer only and don't really talk about what happens if you give your answer to a different number of sig figs (assuming they didn't ask for it to be "an appropriate ammount" or an exact ammount.) Does anyone know what would happen if their answer was like "x=9.2" and you put "X=9.15"?
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smith50
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#1172
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#1172
(Original post by laser174572)
Out of interest, what paper/book is that question from?


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I found it on the web
Smith
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UnknownOrigin
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#1173
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#1173
(Original post by Science211)
Hi, don't know if i'm overthinking this but could someone have a look at june 12 question 1)a) i seem to be getting 4.9 K rather than 17K

Thanks
Q = mc deltaT

We're told that it supplies 8500J per second, and the mass of water flowing through the heater per second is 0.12kg.

8500J = 0.12kgx4200 x deltaT

DeltaT = 8500/0.12x4200

DeltaT = 16.86

So round up for 17K
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UnknownOrigin
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#1174
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#1174
Also, what are people thinking for the six markers for the core/astro papers?

I'm personally hoping for thermal derivation of the pV=1/3NM(crms)^2, cause its mentioned on the spec.

For astro stellar evolution wouldn't be too bad, or comparing the advantages/disadvantages of refracting & reflecting telescopes. Not sure what else is a potential question really...
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Xiomara
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#1175
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#1175
(Original post by Matt III)
This may have already been posted, but in the mark schemes for the mathsy questions they always seem to give one answer only and don't really talk about what happens if you give your answer to a different number of sig figs (assuming they didn't ask for it to be "an appropriate ammount" or an exact ammount.) Does anyone know what would happen if their answer was like "x=9.2" and you put "X=9.15"?
I second this! Always wondered haha.
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laser174572
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#1176
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#1176
(Original post by smith50)
I found it on the web
Smith
Okay, thanks
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Cheezburger
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#1177
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#1177
Please help does anyone know where to find the mark schemes for the June 2010-12 papers? I can't seem to find them on the AQA website
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Hullo
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#1178
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#1178
(Original post by Cheezburger)
Please help does anyone know where to find the mark schemes for the June 2010-12 papers? I can't seem to find them on the AQA website
Sure? They're under the options section they'll have both options and core
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Hullo
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#1179
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#1179
(Original post by Matt III)
This may have already been posted, but in the mark schemes for the mathsy questions they always seem to give one answer only and don't really talk about what happens if you give your answer to a different number of sig figs (assuming they didn't ask for it to be "an appropriate ammount" or an exact ammount.) Does anyone know what would happen if their answer was like "x=9.2" and you put "X=9.15"?
It's not a sig fig question so you shouldn't worry too much, sometimes they'll even put the non rounded figure in brackets in the mark scheme like: 9.2 (9.15) but to be on the safe side just try to do the minimum sig figs in the question
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Science211
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#1180
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#1180
Help on June 12 part A 3)c) anyone? I'm stuck??

http://filestore.aqa.org.uk/subjects...1-QP-JUN12.PDF
http://filestore.aqa.org.uk/subjects...W-MS-JUN12.PDF
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