Interstellar clouds of dust where stars form are known as

Stars form inside relatively dense concentrations of interstellar gas and dust known as molecular clouds.

Explanation:

These regions are extremely cold (temperature about 10 to 20K, just above absolute zero). At these temperatures, gases become molecular meaning that atoms bind together.

answer:

sequence 1- deletion

                  2- duplication

                  3- insertion

                  4- substitute

                  5- inversion