Answer:
The answer is <em>e.2</em>
Explanation:
We should make use of Snell's refractive law. The arriving wave has a certain velocity at T in a medium, then instantly it reaches a medium (same composition) at T' where velocity would either decrease or increase. 
When the incidence angle is 30 °, and we want to make the refraction angle 90 ° such that no sound passes through the barrier (this would be named total internal refraction), so we want the second medium to be "faster" than in the first.
<em>The steps are in the image attached:</em>
 
        
             
        
        
        
Yes because something that has been electrically charged can make other things move without touching them ( this is called force without contact)
Hoped this helped :)
        
             
        
        
        
Answer:
The mass of moon is 1/100 times and its radius 1/4 times that of earth. As a result, the gravitational attraction on the moon is about one sixth when compared to earth. Hence, the weight of an object on the moon is 1/6th its weight on the earth.
 
        
             
        
        
        
Im pretty sure it’s A eye