Which of the following shows geometrical isomerism ? (i)CHCl=CHCl , (ii)CH_2=C Cl_2 , (iii) C Cl_2=CHCl Give structures of its cis- and trans-forms.

Which of the following shows geometrical isomerism ? (i)CHCl=CHCl , (

1.	Which of the following shows geometrical isomerism ? (i)CHCl=CHCl , (ii)CH_2=C Cl_2 , (iii) C Cl_2=CHCl Give structures of its cis- and trans-forms.
Answer» Solution :Only (i), i.e., CICH=CHCl has two DIFFERENT substituents on each carbon atom of the double BOND and HENCE show GEOMETRICAL isomerism. The other two compounds, i.e., (ii) and (iii) do not show geometrical isomerism because one of the carbon atoms of the double bond in each case has two IDENTICAL atoms, i.e., Cl atoms.