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  1. h4rriet

    Physics /12 Discussion!

    No, the ball's OVERALL energy will remain constant throughout. K.E. will turn into G.P.E. and G.P.E.
  2. h4rriet

    Physics /12 Discussion!

    But the PE doesn't increase proportionally with height. That was the option, unless I remember incorrectly? And yes, I chose the option with the 5 N through the centre of gravity too.
  3. h4rriet

    Physics /12 Discussion!

    How about these questions: The SI unit of resistivity. The graph of the voltage across 2 resistors in series (one was a variable resistor and the other a normal resistor). The perfectly elastic collision question.
  4. h4rriet

    Paper 12 Chemistry 11th June 2013 DISCUSSION

    Discussions can be public after 24 hours (so post in this thread tomorrow and NOT today), but if anybody would like to discuss the paper today, message me privately. (ONLY people who've already done the paper; I'll know.)
  5. h4rriet

    Physics /12 Discussion!

    I chose total energy of the ball is conserved. What about the resultant forces question (number 3)? Did the 5 N go through the centre of gravity?
  6. h4rriet

    P1 MCQ's preparation thread for chemistry ONLY!!!!

    Oxygen has 2 paired electrons in its outer shell, one in an s orbital and one in the p. It has 2 unpaired electrons, both in p orbitals.
  7. h4rriet

    P1 MCQ's preparation thread for chemistry ONLY!!!!

    19. It's something to be memorised, not deduced. 27. Warmed with sulphuric acid -> ester turns into carboxylic acid and alcohol. In the second step, H2 is added to to all the C=C bonds. 35. You gotta memorise all this. It's just plain facts.
  8. h4rriet

    P1 MCQ's preparation thread for chemistry ONLY!!!!

    What's the question?
  9. h4rriet

    Chemistry: Post your doubts here!

    With cold, dilute KMnO4, the C=C bond turns into C(OH)-C(OH). With hot, concentrated, it turns into C=O and O=C.
  10. h4rriet

    Chemistry: Post your doubts here!

    If x moles of HI dissociates, then H2 and I2 gain x/2 moles (mole ratio 2:1). Amount of HI left = b-x. Now, Kp=p(I2)xp(H2)/p(HI)^2. [(x/2)*(x/2)]/(b-x)^2 will simplify to D.
  11. h4rriet

    Chemistry: Post your doubts here!

    24. Because of the rings, the compound can't be planar. Because of the rings, there can exist no cis-trains isomers. 8. Pressure depends on the mole ratio, so you'll need to be calculating the moles here. Mass of H2=2 g, molecular mass=2, so n=1. Calculate the total moles in A, B, C and D. C's...
  12. h4rriet

    Chemistry: Post your doubts here!

    Check the mark scheme again. Pretty sure it's Na.
  13. h4rriet

    Chemistry: Post your doubts here!

    23. Ethene is half of the products. So there must be 2 ethene molecules and 1 propene and methane. 3+1+(2x2)=8. The compound that is cracked must contain 8 carbons.
  14. h4rriet

    Chemistry: Post your doubts here!

    What you have to do is draw ICE charts for all the equations (A, B, C and D). Then see if the sum of equilibrium moles is 2+x/2. Here's the ICE chart for D:
  15. h4rriet

    Chemistry: Post your doubts here!

    No, forget about the bonds broken - bonds formed; you can't do it that way. Only ONE compound is made, so all the bonds made are its own, and all the energy of the reaction goes to it and it alone. There are 2 moles of it, so the energy it used to make 2 compounds. To find the energy needed to...
  16. h4rriet

    Chemistry: Post your doubts here!

    It's a cis-trans isomer.
  17. h4rriet

    Chemistry: Post your doubts here!

    2 moles of one compound is broken down. So divide the energy by 2. And then divide what you get by the number of bonds in the molecule.
  18. h4rriet

    Chemistry: Post your doubts here!

    Find the moles of O2 using n=v/24 (don't forget to convert cm3 to dm3). Then write down the equations for the combustion of all the metals. Calculate the moles of all the metals using n=m/Ar. Then use mole ratios.
  19. h4rriet

    Chemistry: Post your doubts here!

    When you write the equation for the decomposition of a Group II metal nitrate, you see that the mole ratio of the metal nitrate to the metal oxide is 1:1. So n(nitrate)=n(oxide). You have the mass of the nitrate and you can find the mass of the oxide (mass of nitrate minus mass of gases). You...
  20. h4rriet

    Chemistry: Post your doubts here!

    When an alcohol is dehydrated, the -OH is eliminated and an H atom from a neighbouring C atom.
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