Which electron shell contains the valence electrons of a radium atom in the ground state?
(1) the sixth shell (2) the second shell
(3) the seventh shell (4) the eighteenth shell

(3) the seventh shell

Explanation:

Let's consider the electron configuration of radium in the ground state.

₈₈Ra: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s²

As we can see, the valence electrons are in the 7s shell, that is, the seventh shell. These are the electrons that participate in bonds.

the millers tale is the answer.

beta decay is the answer