What is the name given to all of the known materials used for comparison in this experiment

Answer;

-Controls

Explanation;

A control is something that is used as a standard of comparison for checking the results of an experiment. A control is important for an experiment because it allows the experiment to minimize the changes in all other variables except the one being tested.

There will frequently be two groups under observation in an experiment, the experimental group, and the control group. The control group is used to establish a baseline that the behavior of the experimental group can be compared to.

-Without an experimental control group, it is difficult to determine the effects of the independent variable on the dependent variable in an experiment.

americans began to notice growing differences between the northern and southern sections of the country. there were more people living in cities in the north, which made it more urban. more people lived on farms in the south, which made it more rural. while many people were farmers in the northern states, there were now other ways to make a living, such as working in mechanical cotton gins factories manufacturing cloth, tools and other goods. people in the north supported high tariffs on goods imported from europe because the extra cost encouraged people to “buy american” instead. in the southern states, planters did not like tariffs because they sold most of their production to europe and bought their tools from there as well. southerners believed the protective tariff was something that only northern factory owners keep their profits high. so the southern politicians came up with an idea. they would opt out. they would simply ignore the protective tariff. it was ‘null and void’ in south carolina. the state would not collect the taxes on goods imported into south carolina, no matter what the president said they had to do. this decision led to the nullification crisis.