Midterm taking place outside of scheduled class time

Hello everyone,

As the title suggests, I have a midterm coming up tomorrow that spans past class time. It is an online course that is scheduled from 1:00-2:30, however the professor has said the exam will open at 12:00pm and be due at 3:00pm.

I have a class that goes until 12:50, and being concerned about missing out on 50 minutes emailed the professor questioning them on the fairness of the schedule. Their response was that "The exam should not take more than 80 minutes to complete" - The exam is over 130 MC questions in length, and I know I would very much appreciate the extra time to work on it. Simply put some students will have longer to work on the exam than others because of their course schedule.

Hoping for some insights on where to go from here. Would contacting the chair of the department be an appropriate response? Thanks in advance.