What is a supplementary? How would writing this supplementary improve your knowledge of Physical Chemistry? Failing the course means you have no academic course credit for the course. You should determine why you failed the course. Then, knowing this, review any skills and knowledge needed and then enroll in Physical Chemistry (a second time)/again. Being behind by one year may be necessary in order to earn your degree goal. If Chemistry is your major field of study, you might want to change major fields (but not necessarily).