Answer: cell membrane 
such as water, micro-organism
 physical process 
simple diffusion, osmosis and filtration 
such as potasssium permaganate in water,urea a liver waste diffuses from the body and the kidney help in filtering it out
physiological processs 
active transport, phagocytosis and pinocytosis
such as soduim-potassium pump, exocytosis
Explanation:  transportation in and out of cell is done in different ways listed above but a barrier to this movement is the cell membrane which is an outer covering of the cell. it protect the cell and only some materials can penetrate the cell membrane e.g micro-organism, water e.t.c. the various physical and physiological processes are the various ways substance  cna be liquid, solid or gas are transported within or outside the  cell e.g food
 
        
             
        
        
        
10
In one molecule of N2H4 (Hydrazine), there are two nitrogen atoms.
So, to find how many there are in five molecules, multiply by five.
2 x 5 = 10
 
        
             
        
        
        
A or B I think 
Hope this helps!