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  1. #1 natural science 
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    is anybody can help me with this question plz


    At sea level, there are approximately 2.6 × 1025 molecules m-3 of the atmosphere.
    One of the gases making up the atmosphere has a concentration of 2.21 × 1022 molecules m-3. What is the concentration of this gas expressed in parts per million (ppm)?
    The concentration of this gas ={(2.21× 1022)/(2.6× 1025)}×(1× 106
    =850 ppm
    Superscript (↑)

    still incorrect help please


    Last edited by vanya; October 22nd, 2012 at 04:13 AM.
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  3. #2  
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    ??


    Last edited by vanya; October 22nd, 2012 at 08:54 AM.
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  4. #3  
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    This looks like homework. We don't just answer those off the cuff. The 2nd table units don't make sense--check that.

    Show you've done some work and thinking about it.
    What's confusing you?
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  5. #4 natural science 
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    Quote Originally Posted by vanya View Post
    is anybody can help me with this question plz


    At sea level, there are approximately 2.6 × 1025 molecules m-3 of the atmosphere.
    One of the gases making up the atmosphere has a concentration of 2.21 × 1022 molecules m-3. What is the concentration of this gas expressed in parts per million (ppm)?
    The concentration of this gas ={(2.21× 1022)/(2.6× 1025)}×(1× 10^6 )


    =850m^-3
    is that correct







    plz help
    Last edited by vanya; October 22nd, 2012 at 08:53 AM.
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  6. #5  
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    is anybody online
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  7. #6  
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    Here's a hint.

    If you want to calculate 4.2% of something, you don't just multiply by 4.2.

    What does "per cent" mean - and what extra step would that require for the calculation of 4.2% of a number?

    Now review what you're trying to do with the problem you've got.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
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  8. #7  
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    Quote Originally Posted by adelady View Post
    Here's a hint.

    If you want to calculate 4.2% of something, you don't just multiply by 4.2.

    What does "per cent" mean - and what extra step would that require for the calculation of 4.2% of a number?

    Now review what you're trying to do with the problem you've got.

    i did not get it please if you explain it again please
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  9. #8  
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    At the risk of making a fool of myself, here's my novice attempt.

    Let's take a number; say 5000. And a percentage increase of 5%.

    5% = 5/100 = 0.05

    5% of 5000 = 5000 x 0.05 = 250

    An increase of 5% of a number 5000 means 5000+250, which gives us 5250. Or if you prefer a more straight forward multiplication, 5% increase means to multiple a number by 1.05. Therefore, an increase of 4.2% means to multiple by 1.042.

    2000 increase by 4.2% = 2000 x 1.042 = 2084. Of which the increase was 84.


    edits: To go a step further,

    Year 1: 200
    Year 2: 350
    ...
    Year 10: 730

    The % increase between Year 1 to Year 2 is 175%
    (350/200) x 100 percent = 175%

    The % increase between Year 2 to Year 10 is 208.57%
    (730/350) x 100 percent = 208.57%
    Last edited by scoobydoo1; October 21st, 2012 at 04:14 AM.
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  10. #9  
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    OK. Per cent means per hundred.

    So 4.2% = 4.2/100 or 4.2 divided by 100.

    Dividing by a hundred is the same as multiplying by 0.01.

    As a number therefore, 4.2 per cent = 0.042 .

    Clearly, from this, the calculation you showed at #4 would be rewritten as 0.042*1630.

    The answer to that is 68.46, not 6846. (Unless you're using some form of notation I'm not familiar with.)

    See next item for calculating an increase as a percentage.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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  11. #10  
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    OK, I'll give an example other than the problem you're set.

    At year 1950, a car costs $1500.
    At year 1980, a car costs $7500.

    What is the percentage increase? Think for a minute about how you do this.
    ================================================== =======

    The first thing to look at is the increase in terms of the item given, dollars.

    The increase between 1950 price and the 1980 price is $7500 - $1500 = $6000

    Do you know what to do next?
    ================================================== =====
    I've just had a thought.

    If you were my student, I would have taken your calculator and your phone from you and told you that you could only use them when I handed them back to you for a specific calculation.

    At this point in working out a problem, there is no point in using any calculator. You have to be certain that you know what you are calculating.
    -----------------------------------------------------------------------------------------
    In this case, it's pretty clear that you're simply calculating what one number is as a percentage of another number.

    So which numbers from the calculation 7500 - 1500 = 6000 go into the calculation. What is the calculation?

    ================================================== ==============

    Happily, the increase, $6000, is exactly 4 x $1500, the original value.

    What is the whole number 4 as a percentage? It's 400%

    Look back through this a couple of times. Then see if you can apply it to the problem you've got - keep the calculator until last to check your thinking.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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  12. #11  
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    thanks i understant from your explanation but still can not get answer for my question.i did in this way is that correct please help me

    6981-1630=5351
    5351/1630=3.2828
    3.2828×100=328%
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  13. #12  
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    Nice work. Perfect!

    Keep it up.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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  14. #13  
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    thanks guys for your help.
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  15. #14  
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    anyone can help me with the first question please
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  16. #15  
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    First question?

    A lot of people have trouble working with numbers like this. Sometimes it's easier to separate out the "number" part from the "power" part to get a handle on the size of the answer you're looking for.

    Rewrite as two separate calculations and put them back together afterwards.

    {(1022)/( 1025)}×(1× 106) x {(2.21 )/2.6 }×(1)

    Does that work better?
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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  17. #16  
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    the answer will be 850 ppm but there is
    Superscript (↑ under the question maybe because of that the answer will be incorrect if you know how to do it please
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  18. #17  
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    No. The answer isn't 850 ppm on that calculation.

    Work it through step by step.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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  19. #18  
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    Sorry - I was working on something else at the same time. Your result is right on the calculation you gave.

    But there is something very, very odd about some of those numbers. Is this something from a textbook or from your teacher?
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
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  20. #19 natural science 
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    ???????
    Last edited by vanya; October 22nd, 2012 at 08:51 AM.
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    • 21.1×10^22/2.6×10^25=0.85×10^-3 ×1000000=850×10^-6
      how about this ,is it correct help please





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  22. #21  
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    I wrote the answer as =850ppm (thats all i put) but it came back as: my answer was incorrect in some way. It also stated that i may be required to use superscript.

    Can anyone help me please
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  23. #22  
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    now i know the answer thanks guys
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  24. #23  
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    anyone can help me with this 2 question please


    the two scenarios that could possibly lead to no overall change in GMST in this way.

    1· The atmospheric CO2 concentration decreases while the albedo of the surface (which isn't covered by ice and snow) increases.

    2· The atmospheric H2O concentration increases while the solar constant decreases.

    3· The albedo of the surface (which isn't covered by ice and snow) increases while the fraction of Earth's surface covered with ice and snow decreases.

    4· The fraction of Earth's surface covered with ice and snow decreases while the atmospheric H2O concentration increases.

    5· The volcanic aerosol content in the atmosphere decreases while the fraction of Earth's surface covered with ice and snow decreases.






    ??




    Last edited by vanya; October 25th, 2012 at 03:18 PM.
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  25. #24  
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    For question 2, start here. Greenhouse gas - Wikipedia, the free encyclopedia

    Then you need to check the physical structure of each gas you're considering. If a molecule isn't affected by infrared, then it can't be a greenhouse gas. Molecules Vibrate

    If it's monatomic or a simple bonded molecule - then it can't function as a greenhouse gas.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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  26. #25  
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    ????????????????????
    Last edited by vanya; October 25th, 2012 at 03:19 PM.
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  27. #26  
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    Here's the IPCC list of greenhouse gases and ozone depleting compounds. IPCC list of greenhouse gases - Wikipedia, the free encyclopedia Only one gas on the IPCC list appears in the problem you've been given.

    So clearly you're being asked to look at the structure and properties of the molecules listed.
    NO is a minor ozone depleting gas. Nitric oxide - Wikipedia, the free encyclopedia
    Br2. Bromine compounds are extreme ozone depleting gases (we're lucky that we used chlorine based CFCs commercially rather than bromine based BFCs - we wouldn't have had a chance to do anything about ozone because it would have been all gone) Bromine - Wikipedia, the free encyclopedia Why are bromine molecules different from the simple molecules of O2 and N2? If they're not different, then this simple diatomic molecule couldn't be a greenhouse gas because it lacks the same features as oxygen and nitrogen.

    Look at a couple of the others that have non-neat structures, like say, ammonia.. And check their properties to see if they'd be better candidates.

    I strongly recommend a good long look at the site I gave you earlier. Molecules Vibrate

    Check your thinking against the information and see how you approach the problem now.
    KALSTER likes this.
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  28. #27  
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    I wonder if it can be done that Adelady gets an auto *Like* from me every time she posts? Would save me lots of time.
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

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  29. #28  
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    thanks i know the answer
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  30. #29  
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    how about first question
    plz help
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  31. #30  
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    help plz

    The planet Mercury has a mass of 3.302 × 1023 kg and a density of 5.43 × 103 kg m–3. Use this information to calculate the volume of Mercury.
    Volume,


    v=mass/density

    You should give your answer in scientific notation to the appropriate number of significant figures and with the correct SI units.
    Volume of planet Mercury = 3.302× 1023 kg/5.43 × 103 kg m–3
    v =6.1× 1025 m–3

    Superscript (↑)
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  32. #31  
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    Look at your denominator.




    (Your mistake is one reason why I much prefer E-notation)
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  33. #32  
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    ( 3.302/5.43)=0.61, (1023/ 103 )=10^20
    v=0.61
    × 1020 m–3

    how about this is that correct

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  34. #33  
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    Close.
    look at the form of your exponent...does it follow convention?

    What units are density?
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  35. #34  
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    its kg
    i think you will cancel the kg,
    v=0.61× 10^20 m^3
    what do you think about this
    v=0.61
    × 10^20 kg
    m–3
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