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  1. Farheen1201

    Chemistry: Post your doubts here!

    is it B: 2->1->3
  2. Farheen1201

    Chemistry: Post your doubts here!

    Its optical isomerism, except with 2 chiral carbons, so you need to change the position of the bonded atoms to these carbon atoms.
  3. Farheen1201

    Physics: Post your doubts here!

    Yep
  4. Farheen1201

    Mathematics: Post your doubts here!

    10cos(37) = 7.98 m/s I am guessing its 45
  5. Farheen1201

    Physics: Post your doubts here!

    The centripetal force increases with increasing radii. The mud on the edge is the farthest away ergo maximum radii. Hence it experiences greatest force and flies of first. The mud on the disc will also fly off but after the mud on the edge has flown off.
  6. Farheen1201

    How was 9709_w15_qp_32

    As compared to the previous years, it was a pretty simple paper. Vectors and complex numbers could be no simpler. It was pretty scoring.
  7. Farheen1201

    Chemistry: Post your doubts here!

    62.94 ---> X% 64.93 ---> (100-X)% (62.94*X)+(64.93*(100-X)) ---------------------------------- = 63.50 100 62.94X -64.93X + 6493 = 6350 -1.99X = -143 X = 71.8%
  8. Farheen1201

    Chemistry: Post your doubts here!

  9. Farheen1201

    Chemistry: Post your doubts here!

    The impurity is sulfur. Both, NaBH4 and LiAlH4, can be used to reduce carboxylic acid to alcohol. AlCl3 and Al2Cl6 both can be formed because Al2Cl6 is a dimer of AlCl3. Acyl chloride could be used, I guess. And most importantly WELCOME ABOARD. :);)
  10. Farheen1201

    Chemistry: Post your doubts here!

    Find the Mr of the compound, (NH2)2CO ==> 2(14+2)+12+16=60 Unitary method: 2g of H in 60g of Urea Xg of H in 25.6g of Urea X=(25.6*2)/60=0.853g of H Moles of H present= (0.853)/1 =0.853 mol 1 mole has 6.02x10^23 atoms 0.853 moles has X atoms X=0.853*6.03x10^23 X= 5.14x10^23 H atoms in 25.6 g of Urea
  11. Farheen1201

    Chemistry: Post your doubts here!

    It was only for 2 marks. Hoping that the gt is low, it should not make much of a difference.
  12. Farheen1201

    Chemistry: Post your doubts here!

    I honestly don't know, but it seems like the only reaction to fit. Its maybe got to do with the yield. Electronegativity is the ability of an element to attract a shared pair of electrons to itself in covalent bond.
  13. Farheen1201

    Chemistry: Post your doubts here!

    Yeah That was completely out of the blue.
  14. Farheen1201

    Chemistry: Post your doubts here!

    I was hoping for more numericals. Why no moles or kc or kp.:cry: I could lose marks in explainations. The key words and all. For question 1, I had written Van der Waals so many times I was bored of it myself.
  15. Farheen1201

    Chemistry: Post your doubts here!

    The reagent was propanoic acid. X is an amide. (ch3)2nhcoch2ch3
  16. Farheen1201

    Chemistry: Post your doubts here!

    I personally find chemguide.co.uk very helpful for the organic part. Xtremepapers revision section is also available.
  17. Farheen1201

    Chemistry: Post your doubts here!

    I believe the doubts with the first question is solved. As for question 2(c): The radius of the argon atom is given as 0.190 in the data booklet. Then it is a simple substitution to find the volume. To find the volume of 1 mole of argon atoms, you have to simply multiply the volume of one atom...
  18. Farheen1201

    A level Biology: Post your doubts here!

    Assalamu alaikum and good luck to all of you for the paper. Mine's today
  19. Farheen1201

    A level Biology: Post your doubts here!

    he heterotrophs are organisms that feed on other organisms to obtain the organic compounds.
  20. Farheen1201

    October/November 2013 Discussion for results

    there aren't ebooks of the textbooks!
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