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  1. K

    Chemistry Doubts: IGCSE Paper 3

    nope...did you finish yours?
  2. K

    Chemistry Doubts: IGCSE Paper 3

    who would have thought chemistry paper 3 would be easier than the physics paper3.....wow.
  3. K

    Chemistry Doubts: IGCSE Paper 3

    thanks man but why cant moles of lead nitrate be mass/molecular mass? can you tell me why thats wrong? and what concept have you used for it? that 1 mole gives 2 mole thingy
  4. K

    Chemistry Doubts: IGCSE Paper 3

    i think you should just remember iron for haber process and vanadium pentaoxide for contact process :)
  5. K

    IGCSE Chemistry Revision Guide | According to syllabus

    d ude no clue this is how the question was....the answer to 2 is 0.013 and 3 is 4.4g i dont know how they got it.....and i did the same thing you did in 2 but its wrong
  6. K

    IGCSE Chemistry Revision Guide | According to syllabus

    someone link me the hardest chemistry paper ever till now and help me with this question c) A 5.00 g sample of impure lead(II) nitrate was heated. The volume of oxygen formed was 0.16dm3 measured at r.t.p. The impurities did not decompose. Calculate the percentage of lead(II) nitrate in the...
  7. K

    Chemistry Doubts: IGCSE Paper 3

    i think its this -O-[]-O-[]-O-
  8. K

    Chemistry Doubts: IGCSE Paper 3

    another problem help me on this c) A 5.00 g sample of impure lead(II) nitrate was heated. The volume of oxygen formed was 0.16dm3 measured at r.t.p. The impurities did not decompose. Calculate the percentage of lead(II) nitrate in the sample. 2Pb(NO3)2 → 2PbO + 4NO2 + O2 Number of moles of O2...
  9. K

    IGCSE Chemistry Revision Guide | According to syllabus

    dude which variant did you do? they said repeat the steps c to j with incident ray 25 degrees to the left of the normal and you had to find the index again using a and b
  10. K

    IGCSE Chemistry Revision Guide | According to syllabus

    remember the glass slab one where you had to find the refractive index twice? will they cut marks if they are not equal? and i mean not equal by alot i was getting 1.38 in one and 1.6 in the other....but all the distances were accurate and is on the ray trace sheet.what do you think how many...
  11. K

    IGCSE Chemistry Revision Guide | According to syllabus

    hey why does the grade threshold say out of 200 marks when its like 160 marks? do they take out percentages of each paper or something? and were you able to finish the practical in time?what do you think the minimum marks to get A* will be out of 200?
  12. K

    IGCSE Chemistry Revision Guide | According to syllabus

    anyone do the physics practical 52? so freaking lengthy and our school is just stupid. my glass slab was not shaped exactly like a rectangle it was tilting at one edge so i got my refractive indexes different and they didnt even setup the force experiment at the start. im sure no one loses more...
  13. K

    Chemistry Doubts: IGCSE Paper 3

    but why is it different? seems like the same monomers in both but its just reversing or something....ok to make it clearer can you tell me the monomers of both of those?
  14. K

    Chemistry Doubts: IGCSE Paper 3

    wait but the the picture was NH-[]-CO-NH-[|]-CO-NH-{}-CO so isnt it like the same thing? can you clear this up im getting so confused with this....what make this and nylon different? i know that the link is the same but what else? sorry if i sound stupidly confused :/
  15. K

    Chemistry Doubts: IGCSE Paper 3

    help i always get stuck in these b) The structure of a typical protein is drawn below. (it was just a picture of an amide linkage) (ii) Draw the structural formula of a man-made polymer with the same linkage.
  16. K

    IGCSE Chemistry Revision Guide | According to syllabus

    you have no idea how much this has helped me....im actually kind of shocked about how much i couldnt understand when i read the textbook....this is clearing everything up for me and now it seems easier!
  17. K

    IGCSE Chemistry Revision Guide | According to syllabus

    i owe you big time dude im just gonna learn from this **** the textbook! wait....is that a good idea? :P
  18. K

    Chemistry Doubts: IGCSE Paper 3

    hey i need to know whats important to know in organic chemistry that most likely comes all the time because it always screws me up :( also tell me how to solve questions like these where you have to show alternate products Q.Chlorine reacts with butane in a substitution reaction. CH3—CH2—CH2—CH3...
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