4. Describe what control groups, dependent variables, and independent variables are. Give an example of each.

Control groups - does not receive anything (stays the same)
Dependent Variable - a variable whose value depends on that of another
Independent Variable - whose variation does not depend on that of another
Examples:
Height is dependent
Fertilizer is independent
Plants not receiving fertilizer are the control group

Qrepresents joules in the formula

Radon-222 or rn-222 has a half-life of 3.82 days. to determine the fraction of an original sample of rn-222 that remains unchanged after 7.646 days, we calculate the amount of rn-222 remaining after 7.646 days and divide it with the original amount. using 1 gram as a basis and using half-life calculation methods, we can determine that  0.249 or 0.25  grams of rn-222 will remain, and thus the fraction remaining is 0.25 or 1/4.