The correct set of four quantum number for the unpaired electron of th

1.	The correct set of four quantum number for the unpaired electron of the element Z = 21 is
Answer» `N=3 , l =2 m =1 s=+1/2` `n=3 , l =1 m =0 s=+1/2` `n=3 , l =3 m =2 s=+1/2` `n=4 , l =0 m =0 s=+1/2` Solution :The element Z = 21 is SC. Electron configuration of it is : `Is^(2) 2s^(2)2p^(6) 3s^(2)3p^(6) 4S^(2) 3d^(3)`The unpaired electron of Z - 21 is `3d^(3)` (i) n = 3 = principal quantum number (ii) d orbital has l=2 (iii) as l=2 values of m =+2,1 ,0,-1 ,-2 `therefore` m=+1 is possiblebut only(A)has l=2 (iv) firstelectronin 3d has spin quantum no =+`1/2` thus n=3, l=2,m=1 and s=`+1/3`

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