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  1. L

    Sorry, forgot to reply. :s Actually, those 3 were my best papers and were very good by my...

    Sorry, forgot to reply. :s Actually, those 3 were my best papers and were very good by my standards so I did expect an A* in them. But they must have been high A*s I think.
  2. L

    Chemistry: Post your doubts here!

    20 How many alcohols (including both structural isomers and stereoisomers) can have the molecular formula C4H10O? A 3 B 4 C 5 D 6 The answer is apparently C.. but I can only draw 4 (none of them being stereoisomers) and every website I've read so far says there's only 4 isomeric alcohols of...
  3. L

    Chemistry MCQ?

    Immediate distillation means that ethanol was converted to ethanal, not ethanoic acid. 46g of ethanol gives you 44g of ethanal. 2.30g of ethanol would therefore give you 2.2g of ethanal. But the yield was only 70%, so you get 70/100 * 2.2 = 1.54g of ethanal.
  4. L

    Chemistry: Post your doubts here!

    PV = nRT V = nRT/PV Moles of water used = Mass/Mr = 1/18 = 0.056... V (in cm^3) = (0.056 * 8.314 * 596) / (101 x 10^3) V = 2.72 dm^3 So C is right. It's off by a little but the only option close to it is C. Also, remember that you have to use SI units in the formula.
  5. L

    Chemistry: Post your doubts here!

    They said only 1 mole of the metals was burnt. A is wrong because there would be problems with the vertical scale. The first reading would HAVE to be 0.5, but the other 2 would have to be increased by 0.25.
  6. L

    Its raining suggestions! Advancing XtremePapers, Advancing Knowledge

    I use Opera 11.62.
  7. L

    Honestly just practice past papers to the extent that you get like 80+ % in them and you should...

    Honestly just practice past papers to the extent that you get like 80+ % in them and you should be good to go. In Chemistry I made lots of blunders in P2 and P4, and for P1 I guessed like 10 MCQs, lol. :P
  8. L

    help with an extra sub.

    Yeah that policy was enforced this year, I think. It sucks, but meh. :( I am not sure what you should do in that case though.. try to talk to your school about it anyway maybe?
  9. L

    Chemistry: Post your doubts here!

    Trigonal planar is when there are 3 bonds and no lone pairs, like in AlCl3.
  10. L

    Its raining suggestions! Advancing XtremePapers, Advancing Knowledge

    Why is there a confirmation box when you try to 'Like' something? Seems useless IMO.
  11. L

    ~~jokes?? in here?? really??

    This is awesome, I remember seeing a similar picture somewhere else before.
  12. L

    May/June 2012

    ^ Looking at the above post, I am SO glad I don't have to touch Pak. Studies anymore. :) Anyway, I'm giving AS level Maths, Chemistry and Physics only.
  13. L

    help with an extra sub.

    Wait, I thought from now onwards you can't give one exam privately and others through school, it either has to be all privately or all through school. I think you should talk to your school about it.. And yes, Pak. Studies is just one subject. :P
  14. L

    Mathematics: Post your doubts here!

    The expansion is 32 - 80y - 80y^2 According to the 2nd expression they provided, y = 2x - x^2 Replace y in the 1st expression with 2x - x^2 and you will get your answer.
  15. L

    Chemistry: Post your doubts here!

    Yeah, you are right. Actually, my teacher told me that 3 bonds and 1 lone pair are approximately 107, and since B and C were quite close to each other I thought C would be correct. Confusing question IMO.
  16. L

    Chemistry: Post your doubts here!

    What are the bond angles in the PH3 molecule likely to be? A) 90 B) 104 C) 109 D) 120 Question is Q7 from Winter 2004, ']http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w04_er.pdf PH3 has 3 bonds and 1 lone pair, so I thought the bond angle...
  17. L

    Chemistry: Post your doubts here!

    I am not sure if this is the right way to solve it, but I got the right answer with it so.. C6H12 + 9O2 -> 6CO2 + 6H2O So you have 6 moles of CO2 and 6 moles of H2O. P will absorb all of the mass of H2O, while Q will absorb of all of the mass of CO2. Their masses are 6(18) and 6(44)...
  18. L

    Chemistry: Post your doubts here!

    B is right because all of the other 3 diagrams are wrong. In A, the bond length increases because the bond energies decrease. In C, the B.P increases with increasing # of electrons. And D is wrong because the HX energies decrease (you can even check this in the data booklet). ... And B is...
  19. L

    Chemistry: Post your doubts here!

    lol.. these are long, remind me to get back to them in a bit. :P
  20. L

    Chemistry: Post your doubts here!

    Free radical substitution is homolytic, therefore A and B are wrong. Also, the probability of 1-chloropropane being formed is more than 2-chloropropane because the Cl radical can attack 6 possible hydrogens for 1-chloropropane to form, but only 2 for 2-chloropropane. So the ratio is 3:1, and...
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