chemiy mcq 2009 oct/nov cie

[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]

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

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]

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

One thank you is more than enough

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