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  1. queen of the legend

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

    ehmm ...any1 having doubts can inbox me ...the thread is too messed up ..its difficult to look for those who posted questions
  2. queen of the legend

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

    ok the way i have thought of it without any calculation ....how many electrons does carbon want = 4 ...how many will Al lose 3 so if we have 3 Al x 4 = 12 electrons and no. of carbons will be 4 x 3 = 12 :p i knw its kinda wierd but when u got thinkk out of the box smtimes nd if ur lucky enough...
  3. queen of the legend

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

    The equation below represents the combination of gaseous atoms of non-metal X and of hydrogen to form gaseous X 2H6 molecules. 2X(g) + 6H(g) → X2H6(g) ΔH = –2775 kJ mol–1 The bond energy of an X–H bond is 395 kJ mol –1. What is the bond energy of an X–X bond? ans :+405 how ?
  4. queen of the legend

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

    write down the equation for decomposition of CaCO3 ---------> CaO + CO2 Mr: 100 g gives 44 g of gas hence a total of 1200 g limestone will yield 44 x 1200 / 100 = 528 approximatyely B
  5. queen of the legend

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

    i'll answer them again : q2 : there should be a distribution of energies starting frm zero onwards ...and an increse in temp shifts the molecular energis to the right but area under the two curves should be same since ther no. of molecules remains the same q:4 use equation of bonds broken -...
  6. queen of the legend

    Chemistry P1 Challenging Questions Preparation

    no dear .... Mg is +2 oxygen is -2 and one hydrogen or each hydrogen is +1 to calculate ox. state of hydrogen +2 + (-2 x 2 ) + 2x =0 2x is 2 hydrogen so x = +1
  7. queen of the legend

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

    all these questions have already been discussed chack the previous pages of this thread except 8 10 and 11
  8. queen of the legend

    Chemistry P1 Challenging Questions Preparation

    the HClO ....ok we know that oxugen has -2 ox.state and hydrogen must be +1 .....to find for chlorine use this -2 +1 +x = 0 since there is no overall charge n the molecule so x = +1 hence H and Cl have similar ox.state
  9. queen of the legend

    Chemistry P1 Challenging Questions Preparation

    the OH can be attached on either side considerign that carbon no.2 so a third one results but-2-ene as well
  10. queen of the legend

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

    question paper?????????
  11. queen of the legend

    Chemistry P1 Challenging Questions Preparation

    use mc x delta T 200 x (66-18) x 4.2 = 40320 ok they tell u that 45% is absorbed by water ...so 40320 energy is actually only 45 % of the energy already relased ..so to calculate 100 % which is released u do a reverese process divide 40320 by 0.45 = 89600 .......then they ask for (per...
  12. queen of the legend

    Chemistry P1 Challenging Questions Preparation

    q9 i cudnt get thre right answer (n) q20 : you get 3 hydroxy groups ( one is already present) and teo from the reaction between cold KMnO4 on alkene producing a diol. number of 6 membered ring remaining means how many rings now remian in the whole structure consisting of 6 bonded elemnets...
  13. queen of the legend

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

    13 In aqueous solution, the acid HIO disproportionates according to the following equation where m, n, p and q are simple whole numbers in their lowest ratios. mHIO → nI2 + pHIO3 + qH2O This equation can be balanced using oxidation numbers. What are the values for n and p? ans...
  14. queen of the legend

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

    i guess this is a chemistry paper 1 thread if i am not mistaken!! please ask for physics questions in the physics thread !
  15. queen of the legend

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

    q2: phosphorus is well know ...it has 3 unpaired electrons in its p sub shell : 1s2 2s2 2p6 3s2 3p3 q3: write down the electronic configuration of the three elements q4: when bonds are broken energy is absorbed ( + sign) ...when bonds are formed energy is released (- sign) q6 : in NH4NO3...
  16. queen of the legend

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

    7 Flask X contains 5 dm3 of helium at 12 kPa pressure and flask Y contains 10 dm3 of neon at 6 kPa pressure. If the flasks are connected at constant temperature, what is the final pressure? A 8 kPa B 9 kPa C 10 kPa ans is A ...how ?
  17. queen of the legend

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

    hmm no coz sulfur can form another oxide thats is SO3 ..and which requires 3 moles of O2
  18. queen of the legend

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

    for the 2006 question : i did not understand it myself ! (n) but the 2005 question 12 its very simple: make all no. of moles of elements equal or 2 (just to compare easily) 2 Mg + O2 --------> 2 MgO 2Al + 1.5 O2 ---------> Al2O3 2...
  19. queen of the legend

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

    10 The value of the equilibrium constant, Kc, for the reaction to form ethyl ethanoate from ethanol and ethanoic acid is 4.0 at 60 °C. C2H5OH + CH3CO2H CH3CO2C2H5 + H2O When 1.0 mol of ethanol and 1.0 mol of ethanoic acid are allowed to reach equilibrium at 60 °C, what is the number of moles of...
  20. queen of the legend

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

    Given the following enthalpy changes, I2(g) + 3Cl2(g) → 2ICl3(s) ΔHo = –214 kJ mol–1 I2(s) → I2(g) ΔHo = +38 kJ mol–1 What is the standard enthalpy change of formation of iodine trichloride, ICl3(s)? A +176 kJ mol–1 B –88 kJ mol–1 C –176 kJ mol–1 D –214 kJ mol–1 ans is B ...can sm1 expalin plss
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