Can someone please help me. Like I don’t know if it’s a physical change or chemical change. Is it a physical or chemical change and why is it that change.

Working with si (metric) units for each of the following commonly used measurements, indicate its symbol. liter gram milliliter kilogram meter centigram milligram centimeter kilometer second millimeter milliseconds

Can someone me with questions 15 to 17 plz.

This classification of drug typically changes the brain's chemistry and reduces its ability to create its own endorphins.