Answer:closed systems
Explanation:
A closed system is one in which matter does not enter or leave the system but there is exchange of energy between the system and its environment. In a closed system, the principle of energy conservation applies. The principle of energy conservation states that energy can neither be created nor destroyed but is converted from one form to another. An example of a closed system is a reaction vessel whose lid is closed.
 
        
                    
             
        
        
        
<span>to preserve foods, dye fabric, and DE-ice roads i hopes this helps
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Answer:
a
  
b
 
Explanation:
Generally the force of attraction between this two irons is mathematically represented as 
 ![F =  \frac{k *  [Q_{Li}  ] * [Q_{O}  ]  }{ r^2}](https://tex.z-dn.net/?f=F%20%3D%20%20%5Cfrac%7Bk%20%2A%20%20%5BQ_%7BLi%7D%20%20%5D%20%2A%20%5BQ_%7BO%7D%20%20%5D%20%20%7D%7B%20r%5E2%7D)
Here k is known as the proportionality constant with value 
 substituting -2 for  i.e the charge on oxygen , +1 for
 i.e the charge on oxygen , +1 for  i.e the charge on Lithium and
 i.e the charge on Lithium and ![[0.140 + 0.068 ] nm= 0.208 nm =  0.208*10^{-9}](https://tex.z-dn.net/?f=%20%5B0.140%20%2B%200.068%20%5D%20nm%3D%200.208%20nm%20%3D%20%200.208%2A10%5E%7B-9%7D%20%20%20) for r
 for r 
So
 
 
Generally the force of repulsion will be the magnitude but different direction to the force o attraction 
So Force of repulsionn is 
 
 
 
 
 
 
        
             
        
        
        
Answer: velocity
Explanation: it's the rate of change of the objects position/ consistent change