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O Level Chemistry & IP Chemistry Notes by 10 Year Series Author – Chemistry Specialist

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O Level Chemistry Question: Mole Concepts / Mole Calculations

Try this Mole Concepts O Level Chemistry questions:

Question:
If 2g of hydrogen gas contains x molecules, how many molecules would 2g of nitrogen gas contain?

A) x
B) 7x
C) x/14
D) x/28

Show me the working briefly on how you derive your answer. This way we can determine your concepts for this chapter.

ps: Leave your suggested answers in the “Comments” section below.

Rgds
Sean

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  • O Level Chemistry: Mole Concepts / Chemical Calculations
  • O Level Chemistry: Mole Concepts / Chemical Calculations

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Comments

  1. Sean Chua says

    October 2, 2007 at 5:15 pm

    Halo Students,

    Well Done to all for at least even bother to try it out and sharing with fellow students.

    Yup. Answer is indeed C, x/14.

    linwood-you can refer to the 2 answers given by robobooga and lijun. Do let me know if you need clarification on it. Stay positive and cheerful as you prepare…

    =)

  2. LinwooD says

    October 2, 2007 at 5:56 am

    hmm i guess it’s x/14 too.
    i thought its about molar mass.

    so what’s the right answer actually ?????

  3. lijun(: says

    October 1, 2007 at 4:01 pm

    No. of moles of H2 = 2/2 = 1mol
    No. of molecules of H2 = (1)(6*10^23) = 6*10^23

    let 6*10^23 = x

    No. of moles of N2 = 2/28 = (1/14)mol
    No. of molecules = (1/14)(6*10^23) = x/14

    hence, answer is C.

    is it right?

  4. robobooga says

    October 1, 2007 at 1:19 pm

    hmm… i try…

    2g of hydrogen gas = 1 mol =x

    2g of nitrogen gas = 2g/28g =1/14 mol

    therefore, if 1 mol is x, then 1/14 mol = x/14 #

    correct?

  5. LinwooD says

    October 1, 2007 at 7:03 am

    Well, i will try to answer this question.

    2g of hydrogen gas = 2H2 = 4 = x
    2g of nitrogen gas = 2N2 = 2×14 = 28

    28/4=7

    since 4=x, therefore,
    nitrogen gas is 7x.

    well, i dont know whether i did correctly or not though. please correct me if i’m wrong. 😀

  6. LinwooD says

    October 1, 2007 at 6:19 am

    hello, who are you? you left me a comment yesterday. anyway, you have a good heart to make this blog :). it helps O level students a lot. especially me. haha.

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