What is biodiversity? I don't really understand...

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

What element has similar physical and chemical properties as boron.

With the largest atoms and the smallest number of valence electrons and with the smallest atoms and the greatest number of valence electrons are the most reactive. a. nonmetals; metals b. nonmetals; transition elements c. transition elements; metals d. metals; nonmetals