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  1. S

    Chemistry: Post your doubts here!

    Okay , in A ethanol with sulphuric acid is a hydrolysis reaction , so ethanol loses a water molecule and nothing happens to sulfuric because I think it acts as a catalyst , thus nothing gains or losses oxygen. In C it's also an example of the hydrolysis of an ester , therefore the ester splits...
  2. S

    Chemistry: Post your doubts here!

    http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Chemistry%20(9701)/9701_w05_qp_1.pdf here you go :D
  3. S

    Chemistry: Post your doubts here!

    I think the answer is B , am I right?
  4. S

    Chemistry: Post your doubts here!

    hey everyone alsallum alaykom , can any one please explain the answer in question 3 OCT/NOV 2005?P1
  5. S

    A level Biology: Post your doubts here!

    Plasma cells produce antibodies , where as memory cells are stored during the primary response and on encountering the same antigen again they divide into more memory cells AND plasma cells which secrete antibodies against the antigen.
  6. S

    A level Biology: Post your doubts here!

    HEY alsalum allaykum , can some one please help me put in question 2 Oct/Nov 2008 32 , how they said to draw five cells and their drawing showing more than that :S I don't understand can some please explain? and what about those dots on the right of the drawing , aren't they chloroplasts??
  7. S

    A level Biology: Post your doubts here!

    When they say the distance between each division on a stage micrometer is for example 0.1mm , do they mean the small divisions or the big divisions?
  8. S

    Chemistry: Post your doubts here!

    No we don't , but if they tell you to write the minimum reaction time then you subtract the uncertainty fro the reaction time and vice versa for the maximum reaction time , hope you got it:)
  9. S

    Chemistry: Post your doubts here!

    the smallest reading in a stop watch would be 1 second so , 1/2 = 0.5 seconds , any one do please correct me if I'm wrong
  10. S

    Chemistry: Post your doubts here!

    Is the unit for 1000/reaction time in seconds , s^-1 or 1000s^-1 ?
  11. S

    Chemistry: Post your doubts here!

    Can some one please tell me how they to solve question 1c in Maj/June 2008 31 varaint?
  12. S

    Chemistry: Post your doubts here!

    O Okay I got it , thanks a lot for the help , jazak alallah 5ayran.
  13. S

    Chemistry: Post your doubts here!

    HEY can some one please check if the answer in the marking scheme in paper May/June 2011 33 for question c is correct , from where they brought the 10 to multiply? can some one pleasee help?
  14. S

    A level Biology: Post your doubts here!

    Whaaaat is it that bad X_X
  15. S

    A level Biology: Post your doubts here!

    No matter how much good the exams go , we always end up with mistakes XD...what about those people with achievers awards don't they get a full mark? :p
  16. S

    A level Biology: Post your doubts here!

    https://www.xtremepapers.com/community/threads/my-notes-for-biology-and-physics-a2.14550/
  17. S

    A level Biology: Post your doubts here!

    you're welcome :D
  18. S

    A level Biology: Post your doubts here!

    any time :)open this link and download marry jones revision guide , there's a whole chapter for practical skills that would be helpful: https://www.xtremepapers.com/community/threads/my-notes-for-biology-and-physics-a2.14550/
  19. S

    A level Biology: Post your doubts here!

    Suppose the volume of the solution you want to serial dilute is 10cm^3 you put it in a small beaker okay and in another beaker you add 9cm^3 of distilled water , then by using s syringe you take 1 cm^3 from the 10cm^3 solution and you add it to the beaker containing the 9cm^3 distilled water ...
  20. S

    A level Biology: Post your doubts here!

    It's the percentage concentration right?
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