194db is the loudest Sound wave 
        
                    
             
        
        
        
At certain altitude, the temperature of air decrease, The air becomes saturated and water vapour molecules starts condensing.
As the altitude of air increase, the atmospheric pressure decrease due to which the temperature of the air decrease. The water molecules in the atmosphere start condensing, which saturate the air (that is air can no hold water molecules), due to which the water vapour molecules starts condensing and falls on the earth in the form of rain.
 
        
             
        
        
        
Explanation:
1 mega Hertz = 1000000 hertz
 
        
             
        
        
        
Answer:
D. infinitely extended in all directions
Explanation:
A semi infinite solid is infinitely extended in every direction. It has a single surface and can extend when heat is applied. 
The body of a semi infinite solid is idealised, that is, when there is heat present, it expands in all directions to infinity. It can be used for a thick wall because its shape can be changed when subjected to different levels of heat near its surface. 
It is also expands as heat is applied because its thickness is negligible. 
This idealized body is used for earth, thick wall, steel piece of any shaped quenched rapidly etc indetermining variation of temperature near its surface & other surface being too far to have any impact on the region in short period of time since heat doesn’t have sufficient time to penetrate deep into body thus thickness can be neglected
 
        
             
        
        
        
<h2>
Time taken is 0.632 seconds</h2>
Explanation:
Impulse momentum theorem is change in momentum is impulse.
Change in momentum = Impulse
Final momentum - Initial momentum = Impulse
Mass x Final velocity - Mass x Initial Velocity = Force x Time
Mass x Final velocity - Mass x Initial Velocity =Mass x Acceleration x Time
Final velocity - Initial Velocity = Acceleration x Time
Final velocity = 9.9 m/s
Initial Velocity = 3.7 m/s
Acceleration = 9.81 m/s²
Substituting
9.9 - 3.7 = 9.81 x Time
Time = 0.632 seconds
Time taken is 0.632 seconds