Suppose that an intrinsic C-parity factor C_a is introduced into (5.50b), which then becomes Ĉ |α, Ψ} = C_a |α̅, Ψ}  and analogously  Ĉ |α̅, Ψ} = C_α̅  |α, Ψ}. Show that the eigenvalue corresponding to any eigenstate of  Ĉ is independent of C_α, so that C_α cannot be measured.