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Chemistry: Post your doubts here!

Discussion in 'International A And AS Level' started by XPFMember, Sep 29, 2011.

  1. Ayesha Amjad 22

    Ayesha Amjad 22

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    Hi Everyone I would like to post some very inportant notes for cie AS Level Chemistry. Download the notepad file. It contains the link to the website for Chemistry notes AS Levels only
     

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  3. achaaa

    achaaa

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    chemhelp.PNG
    Question 2 b(iii)
     
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  4. Unknown202

    Unknown202

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    upload_2018-1-19_0-46-39.png
    someone plz solve these question answer is A
     
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  5. Unknown202

    Unknown202

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    upload_2018-1-19_0-51-52.png
    why ans is B plzzzzzzzzzz help
     
  6. Unknown202

    Unknown202

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    upload_2018-1-19_0-54-28.png
    and this answer is A why?
     
  7. allexaa99

    allexaa99

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    First, you write out the equation

    2C3H7OH(l) + 9O2(g) -> 6CO2(g) + 8H2O(l)

    0.1 mol of propanol = 2.4dm3

    From the equation:
    2mol of propanol reacts with 9mol of oxygen
    0.1mol of propanol reacts with 0.45mol of oxygen

    0.45mol of oxygen=10.8dm3

    After the reaction,
    Since we have 12dm3 of oxygen (excess), there will be 1.2dm3 of oxygen left.
    7.2dm3 of carbon dioxide will be produced from the reaction.

    1.2+7.2=8.4dm3
     
  8. fahadhameedahmad

    fahadhameedahmad

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  9. fahadhameedahmad

    fahadhameedahmad

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  10. MShaheerUddin

    MShaheerUddin

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    Help please.
     

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  11. fahadhameedahmad

    fahadhameedahmad

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  12. fahadhameedahmad

    fahadhameedahmad

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  13. MShaheerUddin

    MShaheerUddin

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    Sir please answer my one.
     
  14. Unknown202

    Unknown202

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    Sir ur video are soo useful but if u can write for each question the year and paper at the title of the video rather than than at the description cuz it takes time to open each and every video to find the question u want plzz sir
     
  15. fahadhameedahmad

    fahadhameedahmad

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    i will change the format, question number + year in the title
    like this

     
  16. Unknown202

    Unknown202

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    Yea but if u can also add no.of question not only year and qp plzzzz
     
  17. fahadhameedahmad

    fahadhameedahmad

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    yes, the question number would be given at the start
     
  18. corona

    corona

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    The answer is C.

    Boron trifluoride is trigonal planar because Boron has 3 valence electrons, while the nitrogen compound is tetrahedral because nitrogen has 5 electrons and only 3 were used for bonding, leaving a pair of unbonded electrons.

    The compounds form a coordinate bond after reacting, where both the electrons from the nitrogen atom are used in forming the bond. Hence, the configuration for both sections is tetrahedral.
     
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  19. MShaheerUddin

    MShaheerUddin

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  20. MShaheerUddin

    MShaheerUddin

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  21. corona

    corona

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    The answer is A.

    2Mg(NO3)2 ------> 2MgO + 4NO2 + O2

    The ratio of number of moles of NO2 (gas X) and O2 (gas Y) is 4:1

    molar masses:
    X - 46
    Y - 32

    mass = (relative) number of moles * molar mass

    X - 46*4 = 184
    Y - 32*1 = 32

    32/184 = 0.174

    Hence, the ratio of masses is 1/0.174 (A).
     
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