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  1. histephenson007

    A2 Physics | Post your doubts here

    For these sort of questions, I basically have a few rules after practising with them for a while : For frequency modulated waves, Rule 1 - Maximum frequency = Carrier frequency + (amplitude of signal wave)*(frequency deviation) As I come to think of it, it suits the definition of frequency...
  2. histephenson007

    A2 Physics | Post your doubts here

    a) Ah, the monstrous question! I just asked my teacher few days ago. This question is about the conservation of momentum. In question, it says that the kinetic energies of positron and electron are negliblie initially. So, v should be zero (almost). So, we know that initial momentum is zero...
  3. histephenson007

    A2 Physics | Post your doubts here

    A) = I e^-ux = I e^-(0.24)(0.4) = 0.9I B) I (transmitted) = I (incident) - I (reflected) I (transmitted) = 0.9I - ((Z2 - Z1) ^2 )/(Z2+Z1) ^2)) I I (transmitted) = 0.9I - ((1.6-1.4) ^2)/(1.6+1.4) ^2)) I So, I (transmitted) = 0.9I - (1/225) I = 0.896 I Which is again, almost equal to 0.9I C) =...
  4. histephenson007

    A2 Physics | Post your doubts here

    I made the same mistake. I guess the question has nothing to do with numbers. It just asks us to "suggest" how we can assume the alpha particles to be constant (with reference to the half-life). That's what I think. Anybody with a better explanation?!
  5. histephenson007

    A2 Physics | Post your doubts here

    It is when the carrier wave frequency is modulated according to the displacement of the signal wave. Am I right?
  6. histephenson007

    Hmm.. last year, I actively participated in the xtremepapers multiple choice revision thread (it...

    Hmm.. last year, I actively participated in the xtremepapers multiple choice revision thread (it went for an epic 150 pages). And did lots of past papers for p2. So I did pretty well in those tests. However, my chemistry teacher was a pregnant, so we weren't able to practise for practicals a...
  7. histephenson007

    Chemistry: Post your doubts here!

    Not to worry, p33's weightage is only around 20%. If u can focus on P1 and P2 these few days, you can still get a very high score. Trust me, it happened to me last year.
  8. histephenson007

    I'm sorry, A in what?

    I'm sorry, A in what?
  9. histephenson007

    A2 Physics | Post your doubts here

    From P to R, can also be seen as : PR = PQ + QR The line PQ is the change in volume and QR is the change in pressure. Then we can just use the formula : W = P(V) W = (24*10^5 ) (6*10-4) = 1440J Please inform me if the answer is wrong
  10. histephenson007

    Chemistry: Post your doubts here!

    There are two possible isotopes for Cl. But the molecule is Cl2. So, there can be three possible peaks. 1. 2 atoms of 35Cl form a Cl2 2. 2 atoms of 37Cl form a Cl2 3. 1 atom of 35Cl and 1 atom of 37Cl form the Cl2. I dunno what the (+) charge on the Cl2 is about. But I think it has something...
  11. histephenson007

    Chemistry: Post your doubts here!

    lol... I was just trying to make sense of the question I dunno the answer to. Maybe my head's starting to rust. Signing off now . Adios
  12. histephenson007

    Chemistry: Post your doubts here!

    I said OH- donor. Hence, a H+ acceptor.
  13. histephenson007

    Chemistry: Post your doubts here!

    FYI, all the text in bold are for A2 level.
  14. histephenson007

    Chemistry: Post your doubts here!

    2,4- DNP ( or phenylhydrazine in this case) is used as a test for Carbonyl groups. The test happens because the hydrogens on the hydrazine group (from the NH2) undergo a condensation reaction with the Carbonyl group (-C=O )to form a water molecule. In compound P, the carbonyl group is the one...
  15. histephenson007

    Chemistry: Post your doubts here!

    I already did that. And I can see my uploaded file in my original answer under attached files. Anyway, its just the same as in the answer sheet.
  16. histephenson007

    Chemistry: Post your doubts here!

    yea, its for A2. Don't worry if your just doing AS.
  17. histephenson007

    Attempted to make sense of that Q8. Have a look

    Attempted to make sense of that Q8. Have a look
  18. histephenson007

    Chemistry: Post your doubts here!

    A. In the reverse reaction of the first reaction, HSO3- acts as a OH- donor. Hence it might be called a base. B. The reaction is SO2 - > SO3- , Sulphur actually got oxidised from +4 to +6. So, its a reducing agent, not an oxidising agent. C. SO3 (2-) accepts a proton in the reverse reaction of...
  19. histephenson007

    Chemistry: Post your doubts here!

    I already uploaded a file. I'm not sure if I uploaded it correctly. How do I upload pictures?
  20. histephenson007

    Chemistry: Post your doubts here!

    glad u understand it and I hate inorganic chemistry. I don't care about it ;p
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