Another name for these two words is "constant" and you want to have a "constant", because you want something to compare your experimental group to, to see whether data had changed or not. So you have placebos or a double- blind to compare your experimental group to it and also so you know you don't have a bias or anything in the study.
The short answer (and the long one for that matter) is physical properties of chemicals. If you are being marked by a machine, likely the answer is going to be physical properties.
Answer: Igneous it forms because of magma but magma is under the earths surface so its Igneous
Explanation:
The pattern of the temperature in a region day by day is called weather. The year by year temperature is a called climate.
