Scientists want to determine if walls that are painted a certain color will raise a person blood pressure they plan to set up four rooms which variable should change in each room

The variable that should change in each room are what colors the walls are painted. This would be the independent variable, or the variable that is being changed in this experiment. The dependent variable would be the data that you collected off this experiment, like the blood pressure. Some control variables that could be in this experiment are the person being used, what machine is testing the blood pressure, temperature, diet, etc.

yes its like the dead sea which is full of salt which makes you stay afloat

so yes an egg will float in salt

halogen, any of the six nonmetallic elements that constitute group 17 (group viia) of the periodic table. the halogen elements are fluorine (f), chlorine (cl), bromine (br), iodine (i), astatine (at), and tennessine (ts).