Answer:
C. Increasing its buoyancy
 
        
                    
             
        
        
        
Electromagnetic waves do not require a medium to travel through. They can travel through empty space or matter.
        
             
        
        
        
Answer:
1 hour to ride his motorcycle
 
        
             
        
        
        
Answer: 
An X-ray is used to take pictures of your bones. The waves that are used are known as radiation waves.
 
        
             
        
        
        
Answer:
Explanation:
You pull a sled exerting a 50 N force on it , sled also exerts a force on you . These forces are action and reaction force , as per third law of Newton . These two forces are equal and  opposite . But they do not act on the same object so they do not cancel each other . They act on different objects , one on the sledge and the other on you . Due to force on sledge , sledge moves in the direction of force or towards you . You will start moving in opposite direction if frictional force of ground is nil or less .