What exactly is a mole?
A mole is the heart of chemistry, essentially. It is the standard unit in Chemistry for measuring large amounts of extremely small substances, like atoms or molecules. In every stoichiometric conversion you do, you will probably use the mol.
What is the difference between average rate of change and instantaneous rate of change at a point?
The average rate of change of some data is essentially the slope: f(b)-f(a)/b-a. This is the slope of a line. The instantaneous rate of change is the rate of change at ONE point, not across the entire function. So, the derivate is found, and say you are trying to find the instantaneous rate of change at time=2 seconds. You would plug your value into your derived equation to find this rate of change specifically at t=2 seconds.
What are some ways I can BEST prepare for the ACT? I feel like time is always out to get me and I need to learn more time management.
Time management is truly the biggest part of the ACT, and it's okay to feel like that. Learning how to work at the problems is extremely important and helpful strategies can be observed so you aren't pushed for time. For example, in the reading section, go to the questions first when your time starts and READ them. Highlight some key words and concepts, so as you start to read the essay, you can start answering the questions as you work your way through.