Mixture should be the answer.
        
             
        
        
        
Explanation:
It is a place where shares of pubic listed companies are traded. ... A stock exchange facilitates stock brokers to trade company stocks and other securities. A stock may be bought or sold only if it is listed on an exchange.
 
        
                    
             
        
        
        
Answer: The correct options are C and E. 
Explanation: When the rattlesnake population increases, the population of grasshopper and prairie dog are also decreases.
Both grasshopper and prairie dog are herbivores and eaten by rattlesnake. When rattlesnake population increases they feed on grasshopper and prairie dog and decrease occurs in their population. 
 
        
             
        
        
        
B, C, D, B
I hope these are right, hope this helped.
        
             
        
        
        
Answer: It is approximately the membrane potential at which the electrochemical gradient for Na+ is zero. 
Explanation:
The charge in plasma membrane occurs with diffusion and electric fields. 
For example, if there are two solutions, let's assume solution X and Solution Y are separated by a porous barrier (to diffuse in equal proportions).
The fundamental principle of diffusion states that solution from a high concentration diffuses to a lower concentration.
For instance, if the X solution contains 40 sodium ions and 40 chloride ions, the Y solution only has 30 sodium and 30 chloride ions. Due to the diffusion, these two solutions will mix and reach a steady-state.
The like charges repel, and opposite charges attract.