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  1. X

    Chemistry MCQ thread...

    1 - when the substance is in water, the -ONa part will become, -O- and Na+ 2 - alkane and alkenes are from crude oil, of course they dissolve in oil 3 - all C are bonded to 4 group hence they are all tetrahedral
  2. X

    Chemistry MCQ thread...

    24 - the hydrolysis of bromoethane is to replace the -Br group with an -OH group - the -OH group is negatively charged. - negatively charge molecules like postively-charged region - nucleus are positively-charged, hence molecules/atoms that like positively-charged regions are called NUCLEOPHILE...
  3. X

    Chemistry MCQ thread...

    18 - my lecturer say that the only alkaline gas we know is AS level is NH3. so just memorise that. - as for the solid residue, sodium salts are all colourless, Fe2+ salts are green. you have to memorise this too.
  4. X

    Chemistry MCQ thread...

    6 - A. bromoethane has a bond angle of 109' whereas the product ethene has a bond angle of 120' B. methane has a bond angle of 109' whereas CO2 is 180' C. methane and chloromethane both has 109 D. ethene is 120' and ethane is 109 so it's D
  5. X

    Chemistry MCQ thread...

    nope, its 2 and 3. SiCl4 dissolves in water to give a strong acid, no ppt
  6. X

    Chemistry MCQ thread...

    answer is C. in C there is a H covalently bonded to an Oxygen atom, hence, hydrogen bonds can form. H bonds are formed when H is covalently bonded to F/O/N atoms. read up on hydrogen bondings.
  7. X

    Chemistry MCQ thread...

    ethanoic acid dissolves partially in water, that's why it's a weak acid it does not have a H that is covalently bonded F/ O /N , so no.
  8. X

    clear my concept....physxx mcq

    well then, if the charge is negative then the force is to the left. and if you move it to the right, you would increase the PE by Fs. u can look at it this way, PE is the energy stored to do work. so if the charge is further away from where it wants to go, then it would have a higher PE. ok?
  9. X

    clear my concept....physxx mcq

    what's the answer for this?
  10. X

    Physics MCQ's Help!!!

    40 - the nucleus absorb an e inside meaning it takes in a negative charge which then neutralise 1 positive charge. so proton number decrease by 1 but inside the nucleus there is one extra electron so the total nucleon number increase by 1. 30 - using Q=It, u get Q= 7200 C. then, 1 Coulomb =...
  11. X

    Chemistry MCQ thread...

    in 3 there is only 1 D, where to find the other 2? they want ND3 not NH3
  12. X

    Chemistry MCQ thread...

    yeah, the answer is B, i just checked. C-H bonds releases the most energy, hence B ( alkane ) has the most C-H bonds.
  13. X

    Chemistry MCQ thread...

    whats the ans? B?
  14. X

    Chemistry MCQ thread...

    C
  15. X

    Chemistry MCQ thread...

    total mass of Ag = 0.216 number of mole of Ag = 0.216/ 108 = 0.002 mole number of atoms in 0.002 mole = 0.002 x avogadro constant = 0.002 x 6.02 x 10^23 = 1.204 x 10^21 total surface area = 150cm3 number of atoms per cm3 = 1.204 x 10^21 / 150 = 8.02 x 10^18 done.
  16. X

    Chemistry MCQ thread...

    answer A
  17. X

    help me in this chemistry MCQ

    when 2 vessel joins together, the total volume becomes 15dm3 using p1v1= p2v2 for vessel X - 5 x 12 = p x 15 - p = 4kPa for vessel Y - 10 x 6 = p x 15 - p = 4kPa hence total P is 4 + 4 = 8
  18. X

    Chemistry MCQ thread...

    D hot concentrated NaOH 3Cl2 + 6NaOH -> 5NaCl + NaClO3 + 3H2O Cl in NaClO3 is +5 - in A and B is -1 - C is -1 and +1
  19. X

    Chemistry MCQ thread...

    try mine. tell me if you guys used the same method
  20. X

    Chemistry MCQ thread...

    because the value can only be calculated theoretically and cannot be carried out practically. 1- because both are solid under standard conditions 2- because methane is in it's gaseous state under standard conditions. since both experiments cannot be carried out, Hess' law is use to calculate...
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