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chemiy mcq 2009 oct/nov cie

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kaipai:
Dear all,
Coudl you explian the answer of the follwing question form chemiy mcq 2009 oct/nov cie:

20 The presence of 11-cis retinal, C20H28O, in cells in the eye is important for vision.
The structure of retinal includes an aldehyde group, a cyclohexene ring and a long aliphatic side
chain, in which a carbon-carbon double bond exists between carbons numbered 11 and 12.
Which statement about 11-cis retinal could be correct?

A. total no. of carbon=carbon double bonds are 5
B.  total no. of carbon=carbon double bonds are 6

Tell me how correct answer is A????I had to modify the question becoz I could not cut/paste the whole question.Plz also tell me how to add questions here by cutting pasting????I struggle to much to write...
Regards,
kpai

Deadly_king:

--- Quote from: kaipai on June 21, 2012, 05:13:13 pm ---Dear all,
Coudl you explian the answer of the follwing question form chemiy mcq 2009 oct/nov cie:

20 The presence of 11-cis retinal, C20H28O, in cells in the eye is important for vision.
The structure of retinal includes an aldehyde group, a cyclohexene ring and a long aliphatic side
chain, in which a carbon-carbon double bond exists between carbons numbered 11 and 12.
Which statement about 11-cis retinal could be correct?

A. total no. of carbon=carbon double bonds are 5
B.  total no. of carbon=carbon double bonds are 6


--- End quote ---

Firstly you should know that cyclohexene has got 3 double bonds!
Just remove the atoms according to the different groups mentionned in the question :
1. cyclohexene : C6H5, one carbon should be free to attach to the long chain
2. aldehyde : CHO
3. Double bond between 11 and 12 C atom : C2H2

In all this makes C9H8O which we remove from the given formula C20H28O.
This leaves us with C11H20

If no more double bonds were there number of H atoms remaining would have been 22. So there is one more double bond which makes it 5 in all : 3 in cyclohexene, 1 between C11 and C12 and one more to balance the number of H atoms

kaipai:
OH Friend :- ::)
All I can say is that now I have run out of words to say thanks to you. EVen if i quote all the synonyms of the english dictionary for 'thank you' I would not be able to actually thank you for your kind and rapid reply........you are wonderful......

Thank you DKING.
Thank you vvvvvvvvvv muchhhhhhhhhhhhh.
Best REGARDS,

K.Pai

Deadly_king:

--- Quote from: kaipai on August 07, 2012, 03:35:56 pm ---OH Friend :- ::)
All I can say is that now I have run out of words to say thanks to you. EVen if i quote all the synonyms of the english dictionary for 'thank you' I would not be able to actually thank you for your kind and rapid reply........you are wonderful......

Thank you DKING.
Thank you vvvvvvvvvv muchhhhhhhhhhhhh.
Best REGARDS,

K.Pai

--- End quote ---

One thank you is more than enough :)

Helping was a pleasure! Now study hard and pass all your exams with flying colours :D

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