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  1. L

    Chemistry: Post your doubts here!

    Be isn't really a typical group 2 element. Like I said before, Be2+ is smaller and has a higher charge density than the other group 2 elements and its charge density is similar to that of Al's. The rest of the group 2 elements are bigger than Al and don't really have a high charge density. Let...
  2. L

    Chemistry: Post your doubts here!

    Bond energy is ALWAYS +ve, so the answer can't be A or B. Also, X2H6 has one X-X bond and 6 X-H bonds. Using formula, you have 2775 = x + (6*395) which is 405.
  3. L

    Chemistry: Post your doubts here!

    Q2) Write down all of the data you have. Mr = 14x + 16y Mass = 0.23 g Moles = 0.23 / (14x + 16y) - (1) Moles = 0.005 (since they said it occupies 120 cm^3) - (2) Equate (1) with (2): 0.07x + 0.08y = 0.23 7x + 8y = 23 And then try each option and see if they add up to 23. In B, 7(1) + 8(2) =...
  4. L

    Chemistry: Post your doubts here!

    A ketone doesn't change the color of potassium dichromate (because it can't be further oxidized), so it can't be A.
  5. L

    Chemistry: Post your doubts here!

    Oh, sorry I was wrong there, it does have a +2 charge. :\ Actually, all of the other elements are larger but beryllium is the only one which has the same charge density as Al. You can figure that out from the data booklet, that's why it said "use of the data booklet is relevant to this question".
  6. L

    Chemistry: Post your doubts here!

    26) Draw all of the structures of C5H10 that have a double or triple bond I think (pi bond means double or triple). There's 6 of them in total. 17) D is the answer because bromine is a weaker oxidizing agent than H2SO4 (H2SO4 is a stronger oxdizing agent than bromine and everything below it in...
  7. L

    Chemistry: Post your doubts here!

    Construct balanced equations for combustion for each of the first 4 alkanes and figure out how much volume you obtain. I'll do one of them to show you how it's like: CH4 + 2O2 -> CO2 + 2H2O 10 cm^3 of CH3 will react with 20 cm^3 of oxygen, leaving 50 behind as residual gas. You also have 10...
  8. L

    Chemistry: Post your doubts here!

    The temperature is being increased, so the vertical height of the curve becomes smaller and the width slightly longer, because the area has to be the same. That means A, B and D are all wrong.
  9. L

    Chemistry: Post your doubts here!

    Hydrolyze the ester to get CH3OH and CH3CH2CH2CO2H (so 3 is obviously wrong). Product #2 will be formed, but it doesn't distill off so you only have the alcohol in the distillate. It's also worth noting that if there was another option - CH3CHH2CH2CO2H in the question, that wouldn't be found in...
  10. L

    Chemistry: Post your doubts here!

    The products obtained by cracking an alkane, X, are methane, ethene and propene. The mole fraction of ethene in the products is 0.5. What is the identity of X? A C6H14 B C8H18 C C9H20 D C11H24
  11. L

    Chemistry: Post your doubts here!

    Same % mass means the same amount of mass of hydrogen and oxygen, so you have 16 Hydrogens and 1 oxygen atom. It's actually a simple question.
  12. L

    Chemistry: Post your doubts here!

    Figure out the oxidation numbers in both N atoms in NH4NO3 and compare it with the oxidation number of N in N2O. Like so: You split up NH4NO3 into the NH4+ and NO3- ions. In NH4+, the charge on Nitrogen is 1 - 4 = -3. In NO3-, the charge on Nitrogen is -1 + 6 = +5. And in N2O, the charge...
  13. L

    Yeah, I don't mind. I inbox'd you my FB account.

    Yeah, I don't mind. I inbox'd you my FB account.
  14. L

    Anytime. :)

    Anytime. :)
  15. L

    Mathematics: Post your doubts here!

    Yeah, like mentioned above you just need to suggest a suitable value. There's a range of answers (like the mean being 40-80 kg and deviation being like 10 kg) so you don't really need to worry about it.
  16. L

    Nope, I never took tuitions. I personally think they are a waste of time, but others will...

    Nope, I never took tuitions. I personally think they are a waste of time, but others will probably disagree with me.
  17. L

    Nah, I don't really get bugged by anything. :P In Maths I used to get like 65-70 in P1 and 80ish...

    Nah, I don't really get bugged by anything. :P In Maths I used to get like 65-70 in P1 and 80ish in P2, but I did much better than that in the CIE paper I think. For physics usually 75-90%. And CS was always 90+. :P
  18. L

    I did really well in CS, Physics, Maths and Addmath past papers but average in Chemistry (like...

    I did really well in CS, Physics, Maths and Addmath past papers but average in Chemistry (like 70ish%) and my Chemistry paper went pretty average too (I must have barely gotten an A I think). Hard to tell in English because the same type of essays that gave me 20ish-24ish out of 30 in school...
  19. L

    Sure. :) Good luck for your papers. When do they start and end?

    Sure. :) Good luck for your papers. When do they start and end?
  20. L

    Most of those who did good in school (and also told me they did good after the papers) got A/A*...

    Most of those who did good in school (and also told me they did good after the papers) got A/A* and some average ones got As while other average ones got Bs, just like you would expect. Just a few of my friends got Cs but they never really performed well in school.
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