How can scientist determine the age of a rock sample using a half-life of a parent isotope?

The bacteria found in soil is usually harmful and measures are taken to remove any traces of microorganisms. true or false

Veins have a much lower blood pressure than arteries. which of these prevents backflow of blood in veins? a. pressure applied by the heart b. one–way valves in veins c. thin muscular walls of veins

A(n) is a molecule influences the way that a molecule reacts.