For n = 2, l will have two values 0,1
For l = 0, ml = 0
       l = 1, ml = -1,0,1
These are the possible combinations.
The n is the principal quantum number
l is the azimuthal quantum number
ml is the magnetic quantum number.
The formula to find the azimuthal quantum number is 
             l = 0,1,2,3 .......n-1
If n = 2, the azimuthal quantum number,
             l = 0 , 1
Then, the ml can be found using the formula,
            ml = 2l +1
For l = 0 , ml = 2(0) + 1 
                     = 1
Therefore, ml will have only one value, which is 0
For l =1 , ml = 2(1) + 1 
                   = 3
Therefore, the ml will have three values, they are -1,0,1
 
Learn more about the quantum numbers in                    
brainly.com/question/16977590        
 
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