What is your reasoning to What set of rules should we use to distinguish between chemical and physical changes in matter?

What is the most appropriate method of gaining weight (muscle mass)

Which of the following requires the use of energy and the of transport proteins to move a molecule across a cell membrane?

Fossils of ancestors of the modern horses show a small 4-toed almost dog-like browsing animal named eohippus over time the horses got larger lost toes and changed to a grazing diet what is the best explanation of why this change occurred