A.C<N<O<F<S B.Si<C<N<O<F C.C<Si<N<O<F D.Si<C<O<N<F
A.n=1,l=0 B.n=2,l=0 C.n=4,l=0 D.n=3,l=2
A.1s22s22p63s23p63d94s2 B.1s22s22p63s23p63d104s1 C.1s22s22p63s23p64s23d9 D.1s22s22p63s23p64s13d10