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Answer the following questions:
   
Answer variants:
Detergent
In a chemical change, new substance is formed.
Hydrogen is more reactive than hydrogen, displaces hydrogen from water. \(2Na\)(s) + \(H_2O\)(l) → \(2NaOH\)(aq) + \(H_2\)l(g)
The solution will become blue, shiny silver metal will get deposited.
   
1. What can be seen when a strip of copper metal is placed in a solution of silver nitrate?
   
 
2. State one basic difference between a physical change and a chemical change.