Salim can balance on his a book on his head while standing on one leg.
what is the conjuction

While

Explanation:

A conjuction is a word that is used to connect sentences or clauses to join phrases or words together.

The word while connects Salim can balance on his a book on his head to standing on one leg since it joins both ideas together by adding an additional fact to what Salim is doing while balancing the book.