Answer:
Radiometric dating, often called radioactive dating, is a technique used to determine the age of materials such as rocks.
They shots sides stoned found six end
You can see a physical change always but not always a chemical
Any given experiment has numerous control variables, and it's important for a scientist to try to hold all variables constant except for the independent variable. If a control variable changes during an experiment, it may invalidate the correlation between the dependent and independent variables.
It’s copied and pasted from google so make sure to put it in your words :)