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2010
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14
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Little Miss Loi avatar

GCE ‘O’ Level 2010 Oct/Nov Chemistry 5072 (MCQ) Paper 1 Suggested Answers & Solutions

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Tuition given in the topic of Little Miss Loi the Science Tutor (archived) from the desk of Little Miss Loi at 2:27 am (Singapore time)

Hello again and unfortunately, the weekend of tuition classes has definitely caused me to keep you non-partying folks waiting for the Pure Chemistry MCQ solutions, and me staying up late to finish them:

2010 O-Level October/November Chemistry 5072 Paper 1 Suggested Solutions

2010 O-Level October/November Chemistry 5072 Paper 1 Suggested Solutions
– click to download

A much more sedate Pure Chemistry Paper 1 compared to the relative mayhem over at the Physics side, though it does have its usual tricks up its sleeve.

In any case, do leave the usual mistake/typo-spotting comment and I’ll try to attend to you once I find the time (admittedly we’re a little behind the comments due to the weekend of classes 🙁 )

Okie good night for now!

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29 Comments

  1. Doe's Avatar
    Doe commented in tuition class


    2010
    Nov
    14
    Sun
    3:12am
     
    1

    Excuse me, do you know how much must i get for paper 2 in order to get a a1/a2 if i scored 30/40 for paper 1? Thanks a lot!

  2. hmmm...'s Avatar
    hmmm... commented in tuition class


    2010
    Nov
    14
    Sun
    7:59am
     
    2

    hey ms loi i'm just a passer by here..
    anyway, why cant question 2 answer be B?
    isnt copper(II) carbonate green? hence, the answer blue ppt formed should be wrong?
    and lastly, could you explain question 12?
    why is it B but not C?

    thank you

    • Ray's Avatar
      Ray replied to hmmm...’s comment


      2010
      Nov
      14
      Sun
      12:01pm
       
      2.1

      @hmmm...: @hmmm... the answer to question 12 is definitely B. The enthalpy change of the forward reaction is between the energy of the reactants to the energy of the products. The question is asking from the peak of the activation energy of the forward reaction to the energy of the products, thus this is the Activation energy plus the enthalpy change of the forward reaction. This it is the Activation energy of the reverse reaction, since haber process is a reversible reaction.

    • J's Avatar
      J replied to hmmm...’s comment


      2010
      Nov
      14
      Sun
      12:52pm
       
      2.2

      @hmmm...: the colour of CuCO3 varies from blue to green, so the choice wasn't wrong. In choice D, NaOH and NaCl will be produced whereby both are soluble compounds. However on the table, it showed that a white ppt will be produced.

      Therefore if youwere to compare in the strictest sense, D is definitely incorrect while B is correct if you give the choice the benefit of doubt that the CuCO3 produced is blue.

      Trick question i would say cause many of my friends jumped into conclusion that B was the answer without observing the remaining choices.

  3. Anon's Avatar
    Anon commented in tuition class


    2010
    Nov
    14
    Sun
    10:46am
     
    3

    Do you know roughly what's the percentage to get A1 for this year's paper? Will the bell curve shift by a lot?

  4. kino's Avatar
    kino commented in tuition class


    2010
    Nov
    14
    Sun
    12:30pm
     
    4

    Hello,
    I have some questions about Q29,
    Why cannot the answer be D?
    Haematite should contain impurity such as sulfur as it was mined.
    The oxygen will oxide the sulfur in the haematite and form sulfur dioxide.
    However, I am not very sure whether sulfur dioxide is considered as the "main gases" or not...
    The another reason I think B is not the answer is nitrogen in air should form oxide of nitrogen due to the high temperature. Thus, the answer should not involve nitrogen gas.
    Thank you m(_ _)m

    • tormented's Avatar
      tormented replied to kino’s comment


      2010
      Nov
      14
      Sun
      3:01pm
       
      4.1

      @kino: Hi kino. For the sulfur dioxide thingy, as what you've said, its not a main gas, partly bcoz haematite contains mainly iron(lll) oxide. And for nitrogen dioxide, as nitrogen(triple bond) is more inert than carbon, more of the oxygen will react with the carbon to form carbon dioxide or monoxide. And also since there are about 70% of nitrogen in air, not all the nitrogen will react with oxygen, even though under high pressure and temp, to give a substantial amount of nitrogen dioxide. So even have nitrogen dioxide form, it will be so little that its not considered 'main gases'. If you are using the Marshall Cavendish Chem Matters txbk by 4 authors, Pg 245 at the bottom last 2 lines lie the answer. Hope this helps. Actually I also wrote D, but nvm.

  5. Kelly's Avatar
    Kelly commented in tuition class


    2010
    Nov
    14
    Sun
    12:37pm
     
    5

    My teacher said A1 is roughly 83%

    For question 2, it should D because there is no way a ppt. would form as all Group 1 metal in compounds will be soluble in water.

    On the other hand, for option B, copper(ii) carbonate can range from blue to green in colour (but more green). But if you look at the question carefully, they said aqueous sodium carbonate, which means the ions present include H+,Cu2+,OH-,CO32-. When added to Copper(II) sulfate, a little blue ppt will appear partly because of the precipitation of copper(ii) ions from cuso4 as the hydroxide ions from sodium carbonate, forming blue precipitate of Copper(II) hydroxide.

    Though the colour is predominantly green, the slight blue ppt that forms should be able to make it less obvious that its enitrely and distinctly green.

  6. butter's Avatar
    butter commented in tuition class


    2010
    Nov
    14
    Sun
    2:29pm
     
    6

    can i ask if anyone knows where i can find h2 chem p3 answers? 🙁

  7. cass's Avatar
    cass commented in tuition class


    2010
    Nov
    14
    Sun
    2:39pm
     
    7

    hie, err..for qn 28, i thought the answer should be C since the silver metal deposited on the copper wire will like prevent further reaction so the mass of the silver crystals should not increase gradually? and is it above mean if i get 36/40 if i count my qn28 wrong? thanks

  8. Gladys's Avatar
    Gladys commented in tuition class


    2010
    Nov
    14
    Sun
    3:23pm
     
    8

    Thx 4 ur explaination J. U must have done well in order to explain to us... I did badly only scoring 21/40... ): how bout the rest of u here?

  9. val's Avatar
    val commented in tuition class


    2010
    Nov
    14
    Sun
    4:51pm
     
    9

    what's the mean score for last year in order to get a1 or a2?

  10. Jax's Avatar
    Jax commented in tuition class


    2010
    Nov
    14
    Sun
    7:03pm
     
    10

    Haiz i got 23/40. What are the chances of a B?

  11. cheese's Avatar
    cheese commented in tuition class


    2010
    Nov
    14
    Sun
    7:48pm
     
    11

    not a bad paper.. i got 38/40. could have gotten full marks T_T!!! hope i can score a A1 hahaha.

  12. Heath's Avatar
    Heath commented in tuition class


    2010
    Nov
    14
    Sun
    8:13pm
     
    12

    Hi miss Loi, do I still stand a chance to get an A1 if I scored 38/40 and 37/40 for chem and physics paper 1 respectively? :/

  13. Sugarrrrush*'s Avatar
    Sugarrrrush* commented in tuition class


    2010
    Nov
    15
    Mon
    4:33pm
     
    13

    Will getting 30-32/40 (give and take that there's a few answers I corrected at the last minute) guarantee me an A? (I don't need an A1, just an A2 will do), considering that I did pretty well for P2 but screwed up the last chem SPA?

  14. Fred's Avatar
    Fred commented in tuition class


    2010
    Nov
    15
    Mon
    7:06pm
     
    14

    Ms loi, can you post the pure bio paper 1 mcq? Thanks in advance 🙂

  15. Anon's Avatar
    Anon commented in tuition class


    2010
    Nov
    15
    Mon
    10:58pm
  16. pearl777000's Avatar
    pearl777000 commented in tuition class


    2010
    Nov
    15
    Mon
    11:26pm
     
    16

    hi miss loi,I'm just passing by n I have doubts abt qn31.shouldn't the answer be helium n not flourine because helium has 8outermost electrons while flourine only has 7?thanks:)

  17. junkbox's Avatar
    junkbox commented in tuition class


    2010
    Nov
    16
    Tue
    12:27am
     
    17

    For bio my answers were CACCC DBBAD AAABC ABDAD CADAA BDBDB ACCCC CADCD

  18. junkbox's Avatar
    junkbox commented in tuition class


    2010
    Nov
    16
    Tue
    12:28am
     
    18

    My bio answers are CACCC DBBAD AAABC ABDAD CADAA BDBDB ACCCC CADCD

  19. Krystal's Avatar
    Krystal commented in tuition class


    2010
    Nov
    18
    Thu
    9:52am
     
    19

    Hi, i'm Krystal. i can't open the files for the gce o level answers. they say we have to change the encoding to make the file readable but none is suitable. do you know what i should do to make the files readable? or could you convert the files and sent them to my e-mail address?

  20. hi's Avatar
    hi commented in tuition class


    2010
    Nov
    22
    Mon
    6:06pm
     
    20

    Hi will you be uploading today's h2 chem paper 1?

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    Nov
    14
    Sun
    5:20am

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