Let's change it just a little by adding a word and removing one and reordering it a bit Among the many challenges students have to face during the winter session is the grammar exam.

It looks a bit off... put "during the winter session" later in the sentence (but not at the end), and remove "with". You "face something" or you "come to face with something" - in the second phrase, "face" is a noun. In your sentence and in the first phrase, it's a verb.

thanks for your help, guys :)

Among the many challenges that the students have to face during the winter session is the grammar.

Among the many challenges students have to face during the winter session is the grammar exam.