Which of the following cannot exhibit isomerism?

Which of the following can not exhibit geometrical isomerism

Which of the following exhibits chain isomerism?

CoCl_(3).6NH_(3) can form 4 different types of complexes (According to Werner). Which of the following cannot exhibit optical isomerism as well as geometrical isomerism ?

Which of the following can exhibit geometrical isomerism?

Which of the following can exhibit optical isomerism?

Which of the following can exhibit geometrical isomerism?

Which of the following can exhibit geometrical isomerism