Ateam of students is performing an experiment to determine how the speed of a reaction between hcl and na2co3 changes with temperature. which aspect of the experiment does not have to be kept constant?

The table below shows the elements that mainly comprise each of the four layers of earth: elements in layers layer main elements crust oxygen, silicon mantle iron, magnesium outer core iron, nickel inner core iron which of these elements make up the layer that is 0.2 to 1.1 percent of earth's total diameter?