Answer:
Space junk is travelling so fast that a collision with an astronaut or a spacecraft could be disastrous.
Explanation:
Space junk orbits the Earth at speeds of about 28 000 km/h.  
That's so fast that even an orbiting fleck of paint has enough kinetic energy to cause impact craters on the surface of a spacecraft. They are even more dangerous to an astronaut on a space walk.
Much of the space debris is larger and more dangerous than a fleck of paint.
One rough estimate of the amount of space debris is
<em>       </em><u>Size</u><em>        </em>        <u>Number of objects</u>
< 1 cm                        200 000 000
1 cm to 10 cm                   700 000
> 10 cm                                 30 000
Satellites, etc.                       18 000
The chances of collision are small, but any collision can be disastrous.
 
        
             
        
        
        
Answer:
The ice chunk will take 2.47 seconds to hit the water.
Explanation:
Height from which ice chunk fell = h = 30.0 m
Initial velocity of the ice chunk = u = 0 m/s
Time taken by ice chunk to cover 30.0 m of height = t
Acceleration due to gravity = g 
Using second equation of motion ;



The ice chunk will take 2.47 seconds to hit the water.
 
        
             
        
        
        
Answer:
A process that involves rearrangement of the molecular or ionic structure of a substance, as opposed to a change in physical form or a nuclear reaction.
Explanation:
Pretty much just not a physical reaction or otherwise 
 
        
             
        
        
        
<span>This means that has great capacity to react with other chemical elements in nature, reacting mainly with sodium, therefore, can only be findings in chemical compounds in most cases. 
hope this helps!.</span>