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  1. Abu mota

    Physics, Chemistry and Biology: Post your doubts here!

    the answer for 26 is D, srry didnt see 2002, i thought it is 2001
  2. Abu mota

    Physics, Chemistry and Biology: Post your doubts here!

    oh srry i thought it is 2001, i didnt see 2002 :oops:
  3. Abu mota

    Physics, Chemistry and Biology: Post your doubts here!

    actually silver is a transition metal too and also iron is too :) it is an exception that silver chloride is white and we know it from the analysis table :D
  4. Abu mota

    Physics, Chemistry and Biology: Post your doubts here!

    which question is that? did he ask for this question?
  5. Abu mota

    Physics, Chemistry and Biology: Post your doubts here!

    yes i am :) because copper doesnt react with hydrochloric acid and zinc does react and so both of these are wrong so the answer must be magnesium and iron :)
  6. Abu mota

    Physics, Chemistry and Biology: Post your doubts here!

    yea Q.22 is quite tricky the answer is A because if u know from the analysis table if u add silver nitrate to chloride ions u get a white precipitate silver chloride :D Q.26 it is C actually D is wrong :D the ms is wrong for J04 Q.19 it is A because aluminium and zinc give the same result with...
  7. Abu mota

    Prediction of Grade Thresholds for May-June 2012!

    in my opinion ur predictions are pretty accurate except for physics way too low and winter examinations for math were harder than this year in my opinion and the gt was 188 :rolleyes: and chemistry i think it was easier than biology so u cud switch them around :p
  8. Abu mota

    Physics, Chemistry and Biology: Post your doubts here!

    hi, i assumed it is chemistry :p so for Q.31 it is B because oxides of nitrogen doesnt come from the fuel, it is caused by the very high temperatures which allow the nitrogen to bond with oxygen, but the carbon monoxide and sulfur dioxide does come from the fuel. for Q.37 it is A because a...
  9. Abu mota

    Physics, Chemistry and Biology: Post your doubts here!

    From which mark scheme?
  10. Abu mota

    Physics, Chemistry and Biology: Post your doubts here!

    it is used because of its high strength to weight ratio, i just saw it on a website :D and there is actually only one mark scheme on the internet sadly :(
  11. Abu mota

    Physics, Chemistry and Biology: Post your doubts here!

    for may/june 2000 Q.17 the difference between them is that Q has a wider opening than P and this can only be caused when the plant has alot of factors than enable it to photosynthesis rapidly like high light intesity or high CO2 concentration and in the question all decrease the rate of...
  12. Abu mota

    Physics, Chemistry and Biology: Post your doubts here!

    i agree with u the ms has lots of mistakes for some reason but i dont agree with u on the question in may 1995 because strength is needed for airplanes as otherwise they will just choose any other metal other than aluminium with a lower density and there are alot, and so what distinguishes...
  13. Abu mota

    POST YOUR BIO AND CHEM PAPER 1 DOUBT HERE !!!!

    srry i did a stupid mistake the answer is B i did it in the same way but i just made a silly mistake, i will explain it again just in case write the formula x+8O2=CO2+H2O and try to balance it with each one until one of them balances, so it is basically trial and error.
  14. Abu mota

    POST YOUR BIO AND CHEM PAPER 1 DOUBT HERE !!!!

    copper will increase but carbon will decrease because when copper is oxidised it will turn into copper oxide which increase its mass however when carbon is oxidised it turns into CO2 which escapes causing a decrease in mass and so the answer is B :D
  15. Abu mota

    POST YOUR BIO AND CHEM PAPER 1 DOUBT HERE !!!!

    is the answer A? i did it with trial and error, i dont think there is another way, i did it like that x+ 8O2=CO2+H2O and then when i tried number 6 on CO2 but it never balanced but when i tried number 5 on CO2, it did balance. did u understand?
  16. Abu mota

    POST YOUR BIO AND CHEM PAPER 1 DOUBT HERE !!!!

    solving past papers in my opinion :D
  17. Abu mota

    POST YOUR BIO AND CHEM PAPER 1 DOUBT HERE !!!!

    MgO cant be reduced by carbon but CuO can be reduced by carbon and so the MgO will stay as it is but the copper oxide will be copper and carbon dioxide and carbon dioxide turns limewater cloudy and so the answer is B
  18. Abu mota

    POST YOUR BIO AND CHEM PAPER 1 DOUBT HERE !!!!

    no bro, he is not plating using the electrodes, you can plate using the electrolytes, the electrode has to be the same as the salt so that we dont change the solution alot, but u can use the electrolyte only. if u dont understand ask again :D
  19. Abu mota

    POST YOUR BIO AND CHEM PAPER 1 DOUBT HERE !!!!

    the percentage of oxygen in the air is 20% and so 30 cm3 will be 20% of the sample of air (as in this reaction only oxygen is used up) and 20/100x=30 then x=150 cm3 :D
  20. Abu mota

    POST YOUR BIO AND CHEM PAPER 1 DOUBT HERE !!!!

    i just explained it on the other sticky page but i will explain it again. well as u know sodium is more reactive than hydrogen and so it will produce hydrogen and not the metal but copper is less reactive than hydrogen and so copper will be produced and so we eliminate 3 and 4, now we have...
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