Mg3(PO4)2 - the molar mass would be 262g/mol, which is 100%
Atomic mass of Mg is 24, since we have 3Mg we multiply by 3 and get a mass of 72
262 : 100% = 72 : x%
x = 72*100 / 262
x = 27.5%
And do that for every element — get the molar mass of P and multiply by 2, use a ratio, and get the molar mass of O and multiply by 8 and use ratios :)
        
             
        
        
        
Theyre the big bunched up group in the middle of the periodic table
        
                    
             
        
        
        
Answer:
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Explanation:
 
        
                    
             
        
        
        
Here we have to get the spin of the other electron present in a orbital which already have an electron which has clockwise spin.
The electron will have anti-clockwise notation.
We know from the Pauli exclusion principle, no two electrons in an atom can have all the four quantum numbers i.e. principal quantum number (n), azimuthal quantum number (l), magnetic quantum number (m) and spin quantum number (s) same. The importance of the principle also restrict the possible number of electrons may be present in a particular orbital.
Let assume for an 1s orbital the possible values of four quantum numbers are n = 1, l = 0, m = 0 and s = 
 .
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The exclusion principle at once tells us that there may be only two unique sets of these quantum numbers:
1, 0, 0, + and 1, 0, 0, -
 and 1, 0, 0, - .
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Thus if one electron in an orbital has clockwise spin the other electron will must be have anti-clockwise spin.