• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

Search results

  1. DragonCub

    need help on CHEM mCqS

    For Q21 you can first set a C atom as the chiral centre. Then, to assure the four gruops linked to it are all different, the only way which uses fewest C atoms is: H, CH3, C2H6 and C3H8. So count the number of C atoms in this alkane: 1 in CH3, 2 in C2H6, 3 in C3H8, and the one as chiral centre...
  2. DragonCub

    need help on CHEM mCqS

    I get it! The answer to Q20 is C. First, it is -cis so B and D are wrong. There is a regular change that, when each C-C bond is replaced by a C=C bond, the total number of H will decrease by 2. Then, suppose an saturated alkane containing 20 carbon atoms. The number of H atoms it has is 20 * 2...
  3. DragonCub

    Need Help!-->>Physics (Oscillations)

    Well it is very close then. 900π mm/s ≈ 2827.4 mm/s ≈ 2.8m/s
  4. DragonCub

    Physics 9702_s06_qp 2

    Yeah... Exactly what the question means.
  5. DragonCub

    Need Help!-->>Physics (Oscillations)

    For the first question, differentiation, I think, is required. The function can be interpreted using trigonometry: d = 15 sin (...) Here d refers to the displacement in mm. The thing in the bracket can be converted from T into radians (not degrees, or the data would not be compatible). The...
  6. DragonCub

    help needed!! 9702_w10_qp 11

    I think to Q12, both momentum (p) and kinetic energy (k.e.) are to be considered. Suggest the masses of X and Y are both M, velocity of X before collision is V Due to momentum conservation, in Experiment 1, before collision, total p = MV + 0 = MV So after the collision total p is still MV - Y is...
  7. DragonCub

    Physics 9702_s06_qp 2

    That's okay. Actually the short-circuit problem is a comparatively serious issue. Imagine, if the whole circuit is shorted, that has the same effect as connecting the two terminals of a cell/battery together, what would happen to the cell/battery? If you have learnt the equation of Electric...
  8. DragonCub

    Physics 9702_s06_qp 2

    Generally, Short-circuit refers to the case that a part of the circuit becomes in parallel to a zero-resistance conductor (almost zero... In reality it requires harsh condition to achieve exact zero). Suggest that a lamp in a circuit is get connected parallel to a wire - the wire has ≈0...
  9. DragonCub

    Physics 9702_s06_qp 2

    For Q7(b) I think that at the beginning we do not know which lamp is faulted. So there is a risk for using the power supply - if the faulted one is Lamp A and the fault is short-circuit, when only S1 is closed the whole circuit becomes shorted can this wuold cause the damage of power supply.
  10. DragonCub

    Physics 9702_s06_qp 2

    The fault is that Lamp C is short-circuited. When S1 open, S2 S3 closed, Lamp B&C are in parallel, and the BC part is in series with Lamp A. So the total R of the whole circuit shoule equal to: R of A + R of BC part. The actual reading shows total R = 15 Ohm, and the R of A is already 15 Ohm...
  11. DragonCub

    What does OCR mean?

    Thanks Math_Angel. Is OCR on the similar knowledge level as CIE? Some of the CIE questions are said to be adapted from that of OCR exams.
  12. DragonCub

    What does OCR mean?

    The attached picture below is scanned from the Pure Mathematics I textbook. What I refer to are the "OCR"s at the right side of the page.
  13. DragonCub

    help with 9702_w09_qp22

    There is a regulation for the experiment results which is that the number of s.f. of calculated results must be equal to the SMALLEST No. of s.f. among the measured values. In other words, the accuracy of the calculated value must be the same as that of the most inaccurate value measured. Here...
  14. DragonCub

    What does OCR mean?

    It is common to see, in the AS&A-level books as well as IGCSE textbooks, right following some of the practice questions, the label sign: (OCR). My teacher says that means the question is a model one for CIE examinations or at least of the same value as a CIE question. But I still want to know...
  15. DragonCub

    Significant Figures

    I was told that the standard requirement of the accuracy to which we round numbers is for most values to 3 s.f. It ought to be generally accepted in all subjects' calculations (mechanics, statistics, physics, chemistry, etc.) There may be some exceptions such as 1 d.p. for angle size (in...
  16. DragonCub

    Chem-doubt!!

    Yeah I agree with that. Some of the strength of the F-F bond can be compensated by the large repulsion between the lone pairs.
  17. DragonCub

    Request Assistance with Physics 9702_s10_qp_21

    Well I'm sure that nearer to the charged unit, stronger the electric field (distant enough from the plate). Does the "decrease" mean decreasing with the direction of the electric field? :?
  18. DragonCub

    Request Assistance with Physics 9702_s10_qp_21

    Guys I got stuck with Question 5 (b)(ii). It's about electric field. Seemed that the information given didn't make sense. Can somebody offer some help or hints, please? Thanks.
  19. DragonCub

    Attendance Register

    Present :D
  20. DragonCub

    Hi everyone!

    Oops it seems my come has brought a deal... :P Anyway I shall appreciate the help & friendship from each of you guys. :D
Top