試題詳解

7. A and B are two elements in the first three periods of the periodic table. In their ground states, the L shell of the atom A has 3 less electrons than the L shell of the atom B. The total number of electrons in the atom B is 5 more than the total number of electrons in the atom A. Which of the following is the chemical formula of the compound formed by A and B?
(A)A₂B₃
(B)A₂B
(C)A₃B₂
(D)AB₄
(E)AB₂