Originally Posted by Saba Arif

Length of thesis statement:
As far as I know, the length of thesis statement should be 1 to 2 lines only.

Placement of thesis statement:
You can write thesis statement anywhere in the introduction. You can write in start, in the middle or at the end. It depends on the nature of essay. Thesis statement mostly placed in the start of introduction.

Identification of thesis statement:
Thesis statement is self-explanatory statement on a topic. It defines your stance or approach on a topic. Examiner can easily pick it.

Thesis statement of "Pollution":
Pollution is a global phenomenon caused by the direct and indirect actions of humans and it has adverse effect on echo system or global environment.

Hope this will help you.