Answer: As long as the two substituents on any one of the two carbons are not the same, it would be capable of cis/trans isomerisim. ===== Explanation: In your example of A--C=C--A, since each of the carbons have an A group and a hydrogen (not shown), it is possible for isomerism (A group is different from H). In your example of B--C=C--A, it is also capable of isomerism because the two groups on each carbon are different (B group is different from H on the first carbon, A group is also different from H on the second carbon). However, if for example, you have a two B groups both attached to the left carbon (without any hydrogens), it cannot be either cis/trans. ***Do note however, that if you have more than two different groups across the double bond overall (ex. Group A, B, and C), you should use the E/Z naming system (organic chemistry) instead of cis/trans. Solution Answer: As long as the two substituents on any one of the two carbons are not the same, it would be capable of cis/trans isomerisim. ===== Explanation: In your example of A--C=C--A, since each of the carbons have an A group and a hydrogen (not shown), it is possible for isomerism (A group is different from H). In your example of B--C=C--A, it is also capable of isomerism because the two groups on each carbon are different (B group is different from H on the first carbon, A group is also different from H on the second carbon). However, if for example, you have a two B groups both attached to the left carbon (without any hydrogens), it cannot be either cis/trans. ***Do note however, that if you have more than two different groups across the double bond overall (ex. Group A, B, and C), you should use the E/Z naming system (organic chemistry) instead of cis/trans..