Answer:
Chemistry definition: Concentration Definition. In chemistry, concentration refers to the amount of a substance per defined space. Another definition is that concentration is the ratio of solute in a solution to either solvent or total solution. Concentration usually is expressed in terms of mass per unit volume.
Dictionary Definition: the action or power of focusing one's attention or mental effort
The symbol for hydrogen is H
Answer:
D
Explanation:
Protons and Neutrons both have a mass of about 1 amu so you add them but electrons have a mass of 0 amu so they are left out.