Question

Which of the following isomer has the highest meltingpoint: 

(a) 1,2-dicholorbenzene 

(b) 1,3 -dichlorobenzene 

(c) 1,4-dicholorbenzene 

(d) all isomers have same melting points

Answer 1

Correct option is (c) 1,4 dichlorobenzene

The melting points of this isomer will be high due to its symmetric structure and it will form most stable arrangement or we can say a good packing by these molecules can be formed. But other isomers have does not have symmetric nature which may cause little difficulty in the packing of each molecule.

So, para isomer is more symmetric than ortho and meta.

Answer 2

Answer is (c) 1,4-dicholorbenzene (para isomers are more symmetric and ortho and meta)