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  1. S

    Chemistry: Post your doubts here!

    RAHMA ABDELRAHMAN , I will see through your questions :)
  2. S

    Chemistry: Post your doubts here!

    SOSO247 OKay , in question 21 the only way to solve it is by drawing the displayed formula of the the compound. the first thing I did is I drew the cyclohexene ring you know how right? in the cyclo hexene there is 12 hydrogen atoms and 6 carbon atoms , then from the sixth carbon atom I drew a...
  3. S

    A level Biology: Post your doubts here!

    Now I get it thanks a lot , JAZAK ILALLAH 5AYRAN
  4. S

    Chemistry: Post your doubts here!

    answer is B amount of sulphite use = conc x vol = 0.1 x (25/1000) =2.5x10^-3mol 2 electrons are lost amount of electrons lost = 2 x 2.5 x 10^-3 ==== 5 x 10^-3 mol amount of electorns gained by metallic salt = amount of electrons lost by sulphite = 5 x 10^-3 mol amount of metallic salt used = 0.1...
  5. S

    Chemistry: Post your doubts here!

    in finding the mass why did you multiply by 1*10^-3 ?
  6. S

    Chemistry: Post your doubts here!

    Okay I rechecked and in Q19 the optical isomer of iii is C*H(I)CH3CH2I the Carbon with the asterisk is the chiral center and u figured out i and ii right? in Q 28 I messed up the double IS broken in A with the addition of hydrogen , but I didn't know that an adldehyde is also oxidised to a...
  7. S

    Chemistry: Post your doubts here!

    thanks a lot :)
  8. S

    A level Biology: Post your doubts here!

    yeah I don't get why to add the differences too :/
  9. S

    Chemistry: Post your doubts here!

    neither do I , I chose B , because I thought that it shows the correct shape of a p orbital which is a dumbbell shape , don't you agree?
  10. S

    Chemistry: Post your doubts here!

    http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Chemistry%20(9701)/9701_w07_qp_1.pdf QUESTION 9 PLEASE ANY HELP ??
  11. S

    A level Biology: Post your doubts here!

    why WHY the time between 1 and 2 and 3 and 4 is the time both the valves are closed??
  12. S

    A level Biology: Post your doubts here!

    0.5 has a higher resolution , because objects of that size can be seen get it?
  13. S

    A level Biology: Post your doubts here!

    What would happen if the pressure potential is equal to the water potential? the solute potential in this case would be lower than the water potential or we can't tell?
  14. S

    A level Biology: Post your doubts here!

    How xylem passes through the apoplast pathway ? Aren't xylem cells dead so there isn't a symplast or apoplast , or because apoplast is between the cell walls which are present?
  15. S

    A level Biology: Post your doubts here!

    hey everyone , alsalum allaykom , can some one help me out in question 38 Maj/June 2004 p1 ? I don;t get how they added the energy used in respiration in photosynthesis and in question 5 I thought that the magnofication of the microscope would be by multiplying 5 with 8 , why is it in correct?
  16. S

    Chemistry: Post your doubts here!

    question 9 , I don't know:eek: any one help??.. question 19 it's A right? draw the displayed formula of the compounds and try to make a chiral center from the elements given to you, if you can't then it won't form an optical isomer , like in iv there's also a double bond and the only carbon with...
  17. S

    Chemistry: Post your doubts here!

    No , a pi bond is the "SIDEWAYS" overlap of two pi orbitals get it :p
  18. S

    Chemistry: Post your doubts here!

    alsalam allaykom , http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Chemistry%20(9701)/9701_w06_qp_1.pdf question 2 , I don't know what to understand from the graph, any help please?
  19. S

    Chemistry: Post your doubts here!

    then why didn't they tell us to refer to the data booklet? the answer B is phosphorous? But how it's p orbital has 1 electron so it lost two electrons but they're asking for the electron configuration of it's second ionisation energy?
  20. 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 question 12 can some one explain the answer , I don't understand how 1.5 mole of an oxygen molecules is needed to react with one mole of aluminum , I thought it's for two...
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