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  1. A

    chem p12...hmm that was a tough one !!!

    It was okay. Mostly the questions were easy, and there were quite a few repeated questions. But there were 4 or 5 hard ones too! :X
  2. A

    Chemistry MCQ thread...

    D? Or maybe B? I'm not sure.
  3. A

    Chemistry MCQ thread...

    A?
  4. A

    Chemistry MCQ thread...

    The standard enthalpy change of formation is the energy required to form one mole of a compound from its elements in their STANDARD STATES and under standard conditions. The standard state of nitrogen is N2 and that of oxygen is O2.
  5. A

    Chemistry MCQ thread...

    Yeah, I got it. ;p Thanks.
  6. A

    Chemistry MCQ thread...

    k. I'm not completely sure, but maybe this is why: You get 0.8 mol of both carbon dioxide and water. So the equation will look something like this: 0.2CXHY + 02 ----> 0.8CO2 + 0.8H20 So, to get 0.8 carbons, X needs to be 4 (0.2 X 4). And to get 1.6 hydrogens Y needs to be 8 (0.2 X 6)...
  7. A

    Chemistry MCQ thread...

    Is it C? If my answer's correct, I'll explain it.
  8. A

    BIOLOGY A LEVEL STUDY GUIDE DOWNLOAD

    Thank you! I hope everyone gets the grades they want. (: And I don't have the chemistry revision guide, nor do I know anyone who has it, sorry. :\ Good luck with whatever exams you have left!
  9. A

    BIOLOGY A LEVEL STUDY GUIDE DOWNLOAD

    Here you go.
  10. A

    Chemistry MCQ thread...

    Nope. 2,4 -DNPH only forms a precipitate with aldehydes and ketones. Other classes of organic compounds (such as carboxylic acids or esters) do not form precipitates. It's just something you gotta learn.
  11. A

    Chemistry notes.

    Some of this is out of syllabus, but I find the tables really helpful for inorganic chemistry.
  12. A

    Chemistry MCQ thread...

    Is it B?
  13. A

    Chemistry MCQ thread...

    Because the number of moles at equilibrium is 1.1, not 1.0. For Kp expressions you need the partial pressures of everything at equilibrium. To figure out the partial pressure of something you need these equations: partial pressure = mole fraction X total pressure mole fraction = number of moles...
  14. A

    Chemistry MCQ thread...

    This is how I worked it out: 2H2O ---> 2H2 + 02 Initial moles 1 0 0 Equilib. moles 0.8 0.2 0.1 total number of moles = 1.1 Mole fraction 0.8/1.1 0.2/1.1...
  15. A

    Chemistry MCQ thread...

    k, thanks guys, I finally got it. ;p
  16. A

    Chemistry MCQ thread...

    Doesn't the [Al(H2O)5OH]2+ ion form when Al2Cl6 is dissolved in water, not AlCl3? Or are they the same thing and I'm just confusing myself?
  17. A

    biO mCqs !!!

    Ah, that's right! I'm so stupid. :X Yeah, I think D too, now.
  18. A

    Chemistry MCQ thread...

    B? 1 and 2 are right, I think.
  19. A

    Chemistry MCQ thread...

    No, it isn't. It's an aldehyde, the oxygen is double bonded to the carbon atom, it has no more available bonds for the hydrogen. The hydrogen is attached to the carbon.
  20. A

    biO mCqs !!!

    A? A negative feedback mechanism, right?
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