If no exact time (such as 15:00 or 21:00) is specified about the deadline and only the date itself is given, does that mean that the Deadline date is inclusive or exclusive?
For example, if the deadline for my Research Project is 10th October (no other exact times are specified) does that mean that I can turn it in on 10th October before it turns into 11th October? Or should I submit it on 9th October before it turns into 10th?
The common meaning in this case is that the deadline expires once the deadline date has been passed. I.e. if the deadline for submission of your Research Project is 11th October you must submit by the end of 11th October.
In business this is taken to mean by close-of-business on the specified date, but such deadlines are often fulfilled by last-minute submission after strict close-of-business, as long as the date is still no later than the deadline date.