Wavelength is the distance between 2 adjacent points in a wave
we can use the following equation to find the wavelength of a sound wave
wavelength = speed / frequency
frequency is the number of waves passing a point in 1 second 
substituting the values in the equation 
wavelength = 343 m/s / 686 Hz 
wavelength = 0.5 m
wavelength of the wave is 0.5 m
 
        
             
        
        
        
Answer:
Explanation:
im sorry if this doesn't help but i think  its A
 
        
             
        
        
        
the greater the <u>mass</u> of an object the more force is needed to cause acceleration
 
        
             
        
        
        
Answer:
u have to purchase it via online e-commerce platforms
 
        
                    
             
        
        
        
They are used to separate mixtures into their component compounds but can no usually be used to deprecate compounds into chemical elements or simpler compounds