Question

how many geometrical isomers of alkene having molecular formula c2f2clBr​

Answer 1

Explanation:

Two or more compounds having the same molecular formula are called isomers. This property is called isomerism.

Geometrical isomerism is alkenes.

Alkenes exhibit geometrical isomerism due to possibility of different geometrical arrangements in space as rotation about.the double bond is restricted,

i)Cis form: If the identical atoms or group lie on the same side of the double bond , the isomer is called cis-form.

ii)trans form: If the identical atoms or groups lie on the opposite side of the double bond, the isomer is called trans-form. 

Answer 2

The supplied alkene has 2 geometrical isomers.

Molecular Formula of supplied alkene:

$\boxed{\sf{C_{2}F_{2}ClBr}}$

So this alkene has one 2 carbon double bond centre , which can give rise to cis and trans isomers.

Diagram:

$\boxed{\setlength{\unitlength}{1cm}\begin{picture}(8,6)\put(3,3){C}\put(3.5,3){\line(1,0){1}}\put(3.5,3.25){\line(1,0){1}}\put(4.75,3){C}\put(3,3){\line(-1,1){0.5}}\put(2.5,2.5){\line(1,1){0.5}}\put(4.95,3){\line(1,1){0.5}}\put(4.95,3){\line(1,-1){0.5}}\put(2.25,2.25){F}\put(2.25,3.5){Cl}\put(5.5,2.25){F}\put(5.5,3.5){Br}\put(3,1){Cis\: Isomer}\end{picture}}$

$\boxed{\setlength{\unitlength}{1cm}\begin{picture}(8,6)\put(3,3){C}\put(3.5,3){\line(1,0){1}}\put(3.5,3.25){\line(1,0){1}}\put(4.75,3){C}\put(3,3){\line(-1,1){0.5}}\put(2.5,2.5){\line(1,1){0.5}}\put(4.95,3){\line(1,1){0.5}}\put(4.95,3){\line(1,-1){0.5}}\put(2.25,2.25){F}\put(2.25,3.5){Cl}\put(5.5,2.25){Br}\put(5.5,3.5){F}\put(3,1){Trans\: Isomer}\end{picture}}$

Important Things To Note:

• In the cis isomer , the two Fluorine atoms will be attached to same side of the respective carbon atoms.

• In the trans isomer, the two Fluorine atoms will be attached to opposite sides of the respective carbon atoms.