Answer:
An atom is stable if the forces among the particles that makeup the nucleus are balanced. An atom is unstable (radioactive) if these forces are unbalanced; if the nucleus has an excess of internal energy. Instability of an atom's nucleus may result from an excess of either neutrons or protons.
Explanation:
 
        
             
        
        
        
Passive transport is a naturally occurring phenomenon and does not require the cell to expend energy to accomplish the movement. In passive transport, substances move from an area of higher concentration to an area of lower concentration in a process called diffusion.
        
             
        
        
        
Answer:
Each component is in balance with the other components. As long as the components are in balance, the ecosystem can remain stable and healthy. Ecosystems may remain stable for many years if the different components are balanced.