`Cl^(-)` has completely filled K and L shells. Explain.

Na^(+) has completely filled K and L shells. Explain?

Cl-has completely filled K, L & M shells. Explain it based on Bhor-Bury theory. (AS_(1))

Copper is regarded as transition metal, though it has completely filled 3d-orbitals. Explain.

(A) : Transition metals form colored ions (R): They have completely filled d-orbitals in the nth shell.

If a radioactive nucleus has a half life of one year, will be completely decayed after two year? Explain.