It is called exothermic reaction because it releases heat and light and it is called combustion reaction because it is reacting and is being oxidised by O2 to MgO.
It can also be called as oxidation reaction since Mg is oxidised to MgO.
        
                    
             
        
        
        
Answer:
 13.4mol of Mg
Explanation:
Given parameters: 
Mass of magnesium = 321g 
Unknown:
Number of moles  = ? 
Solution: 
The number of moles of a substance is given as; 
   Number of moles  = 
  
  Molar mass of Mg = 24g/mol 
  Insert the parameters and solve; 
         Number of moles  = 
   = 13.4mol of Mg
 
        
             
        
        
        
Well, I say the answer is Thermosphere! Hope I helped :) 
        
             
        
        
        
Answer:
6 moles of NaCl are needed to make 3.0 liters of a 2.0 M NaCl solution.
Explanation:
A 2M solution means that there are 2 moles of solute (NaCl in this case) in 1 liter of solution:
1 L solution-----2 moles of NaCl
3 L solution----x= (3 L solutionx2 moles of NaCl)/1 L solution= <em>6 moles of NaCl</em>
 
        
             
        
        
        
Repeatable 
If it’s repeatable and you get the same answer constantly then it’s a good and accurate experiment