C is the correct answer beacause it shows where it is happening in this cas “here”.
        
             
        
        
        
Answer:
v = wavelength * frequency
frequency = 5200 m/s / .2 m = 26000 / sec
20,000 / sec is optimistic for the upper frequency of human hearing
So 26,000 is above the hearing range for human ears
 
        
             
        
        
        
Answer:
 592.92 x 10³ Pa 
Explanation:
Mole of ammonia required = 10 g / 17 =0 .588 moles 
We shall have to find pressure of .588 moles of ammonia at 30 degree having volume of 2.5 x 10⁻³ m³. We can calculate it as follows .
From the relation 
PV = nRT
P x 2.5 x 10⁻³ =  .588 x 8.32 x ( 273 + 30 )
P = 592.92 x 10³ Pa 
 
        
             
        
        
        
Answer:
A. For every action there is an equal and opposite reaction.
 
        
                    
             
        
        
        
I would say B : main sequence is the answer . this is the answer i believe because the star will increase in size and than shine brightly and when it's done , it will get smaller turning into  nebula , eventually exploding sometime around the last stage , but not the last stage of b , c, or d
i really hope that this helps you a lot.