Which of the answer choices is a true statement? select all that apply. nonmetals usually exist as molecules, combining with atoms of themselves. nonmetals can exist on their own as individual atoms. metallic elements usually exist as molecules, combining with atoms of themselves. metallic elements can exist on their own as individual atoms.

explanation:

newton's third law, for every action there is an equal and opposite reaction.

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.