The bridge in the picture is connecting two pleces of land that represents two distinct places. What type or boundary's this?

Which of the following is always a reactant in a combustion reaction? oxygen nitrogen hydrogen carbon

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

In the lab, ammonia was mixed with water to form ammonium hydroxide. what is/are the reactant(s)? o water and ammonia o ammonia o ammonium hydroxide need