Question

Number of geometrical isomers for $1,8$-dichloro-octa-$1,3,5,7$-tetraene are:

• A. $10$
• B. $9$
• C. $8$
• D. $12$

Answer 1

The correct option is A $10$

$Cl-CH=CH-CH=CH-CH=CH-CH=CH-Cl$
Ends are same and even number of double bonds.
Number of geometrical isomers.
$2^{n-1}+2^{\left(\frac{n}{2}\right)-1}$
$=2^3+2^1=10$
Hence, (a) is correct.