Question
Wed April 09, 2014 By: Yash Sahu

A:tetracyanomethane ;            B:carbondioxide

C:benzene ;                                   D: 1,3-buta-di-ene

Ratio of  sigma and pi bonds is in order:

options:

(a)A=B

(b)A=B

(c)A=B=C=D

(d)C

please explain the correct answer.

Expert Reply
Wed April 09, 2014
Option (b) A=B<D<C is correct.
 
In tetracyanomethane, there are total 8 sigma and 8 pi bonds. Hence the ration of sigma to pi is 1:1.
In carbon dioxide, there are 2 sigma and 2 pi bonds, hence again the raio is 1:1.
In benzene, the total sigma bonds are 12 and pi bonds are 3, hence the ratio is 4:1
In 1,3-butadiene, there are c3 sigma bonds and 2 pi bonds , hence the ration is 3:2 or we can say, 1.5:1.
Thus the least ratio is 1:1 of both A and B compounds, then 1.5:1 of D and finally the highest ratio is 4:1 of C.
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