False
Explanation:
Sound waves are longitudinal mechanical waves. 
Mechanical waves are waves that requires a medium to propagate them. 
- A transverse wave is a wave that is propagated perpendicularly to its source. 
- An example is electromagnetic radiation. 
- A longitudinal wave is a wave that is directed parallel to their source. 
- Sound wave is a longitudinal wave. 
- It has series of rarefaction and compression along its travel path. 
- Rarefaction are areas of sparse particles. 
- Compression are areas with dense particles. 
learn more: 
Sound wave brainly.com/question/3619541
#learnwithBrainly
 
        
             
        
        
        
83.9 is the answer i’m pretty sure
        
             
        
        
        
According to this formula :
㏑[A] /[Ao] = - Kt 
when we have Ao = 0.3 m 
and K =0.46 s^-1
t = 20min = 0.2 x 60 =12 s
So by substitution :
㏑[A] / 0.3 = - 0.46 * 12
㏑[A] / 0.3 = - 5.52
by taking e^x for both side of the equation we can get [A]
∴[A] = 0.0012 mol dm^-3
        
             
        
        
        
Answer:
Un río aluvial es aquel en el que el lecho y las riberas están formados por sedimentos móviles y / o suelo.
Explanation:
 
        
             
        
        
        
Complete Question 
The complete question is shown on the first uploaded image 
Answer:
The concentration of  that should used originally is
 that should used originally is 
Explanation:
      From the question we are told that 
          The necessary elementary step is   
                   
           The  time taken for sixth of 0.5 M of reactant to react 
            The time available is 
              The desired concentration to  remain  
 
Let Z be the reactant ,   Y be the first product and X the second product
 Generally the elementary rate  law is mathematically as 
                     
Where k is the rate constant ,   is the concentration of Z
 is the concentration of Z
From the elementary rate law we see that the reaction is second order (This because the concentration of the reactant is raised to power 2 )
  For second  order reaction
             
Where  is the initial concentration of Z which a value of
 is the initial concentration of Z which a value of   
        From the question we are told that it take  9 hours  for the concentration of  the reactant to become 
                  
                   
                         
 
So      
                      
                           
                 =>    
   For   
                 
                 
                            
                             
                              