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  1. histephenson007

    Chemistry: Post your doubts here!

    For competitive inhibition, there is a competition between substrate molecules and the competitive inhibitors for the active site on the enzyme. However, when the substrate concentration increases, there is more probability that a substrate molecule enters the active site. When the substrate...
  2. histephenson007

    Chemistry: Post your doubts here!

    Q3. According to the definition of enthalpy change of ionisation, an electron should be removed from a gaseous atom for first ionisation energy. Two electrons for second ionisation energy. Then, you just have to use the Data Booklet. Adding the first and second ionisation energies of Aluminium...
  3. histephenson007

    Chemistry: Post your doubts here!

    There were so many questions it looks intimidating! I'm not sure about the answers, but this is all the stuff I know. Next time try posting one question at once. First, Oct/Nov 2011 Paper 11 , Q8. I was wrong :( Q19. Answer is A. Bond-making is exothermic, bond-breaking is endothermic...
  4. histephenson007

    Chemistry: Post your doubts here!

    Ethanol + Oxidation agent -----(immediate distillation)----> Ethanal + [(hydrogen gas or water...but that is insignificant)] n (ethanol) = 2.3/ (24+16+6) = 0.05 mol n (ethanol) = n (ethanal) = 0.05 mol therefore, m of ethanal = n (Mr) = 0.05(24+16+4) = 2.2 g But, the yield is 70%. so...
  5. histephenson007

    Chemistry: Post your doubts here!

    Q32 Statement 1 - Obviously disagrees with the sentence 'Carbon monoxide burns readily in oxygen to form Carbon dioxide' Statement 2 - More negative means exothermic reaction (which is easy to occur), so it fits with the sentence Statement 3 - Kc = [product] / [reactant], if this is high means...
  6. histephenson007

    Physics: Post your doubts here!

    http://www.xtremepapers.com/revision/a-level/physics/
  7. histephenson007

    Chemistry: Post your doubts here!

    Read carefully, the D option says solidification! and in the equation it says from (l) to (s). In such case, intermolecular forces are formed, not broken. Since hydrogen bonding occurs in A & B, we may know the answer is C.
  8. histephenson007

    A small mistake in the Physics notes

    I've just been reading through the notes and found a little mistake. You may fix it if you wish. The mistake is : ϕ = h f0 = hcλ0 when the real equation should be ϕ = h f0 = hc / λ0 {because c = fλ , so f = c / λ}
  9. histephenson007

    Chemistry: Post your doubts here!

    Look at those side chains (in the original molecule) carefully, the three of them are equal and have 3 alkene bonds each. ( Overall 9 alkene bonds). Look at the side chains we are to substitute it with : 2 side chains containing one alkene bond and 1 side chain with two alkene bonds. ( Overall 4...
  10. histephenson007

    Physics: Post your doubts here!

    I guess counting squares is the best option available. If not that, you may try using Calculus, but you will need the f(x) of the curve to do that. I kinda suck at counting squares too - -
  11. histephenson007

    you too buddy ;)

    you too buddy ;)
  12. histephenson007

    Biology: Notes for all chapters SUMMARIZED!

    Thank you Sir Cat
  13. histephenson007

    english

    Nah dude, this one can't be done on internet, you need a real person. But trust me, the test is haarddddd damn!
  14. histephenson007

    Applications of Physics and Chemistry.

    I'm strugglin with the same thing as well, I guess I might be able to manage it with past paper practise and reading more into the things I don't understand from them.
  15. histephenson007

    Tips for Chemistry Practicals (P3)

    And remember, if the exam doesn't go well, you can always make up for it by other papers. My practical exam went horribly wrong (d for paper 3 )but I still managed to get an overall a :)
  16. histephenson007

    Chemistry / biology /physics applications

    Sadly, youtube is blocked in China.... TT.TT
  17. histephenson007

    finally started to study..lets get the party started

    finally started to study..lets get the party started
  18. histephenson007

    Chemistry / biology /physics applications

    Is this an actual past paper question? Is it from Biology or chemistry?
  19. histephenson007

    need help forA level bio paper 5 and if you got notes on it , it will be nice :)

    add me to the list plzz
  20. histephenson007

    are A levels really that difficult?

    @elbeyon But many medical schools in UK don't accept re-takes.... so I'm going for a do-or-die physics A levels¬
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