A.9 B.11 C.14 D.16
A.12g B.12 C.1.66×10-27Kg D.1.66×10-27
A.質(zhì)子數(shù)為20 B.電子數(shù)為20 C.中子數(shù)為20 D.質(zhì)量數(shù)位20
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