If you studied hard, I am sure you will pass the exam.
The open condition leaves unresolved the question of the fulfilment or nonfulfilment of the condition (your studying hard), and hence also the truth of the proposition expressed by the matrix clause.
Wait a minute! I am not convinced that it is an open condition. Your sentence means the speaker of I knows the referent of 'you' studied hard but he creates a fiction for the sake of rhetoric where the fulfilment of the proposition is dependent on the truth value of the subordinate clause. Is it a false conditional?