The following observations involving metals A, B, C, and D were made: (1) When a strip of A is placed in a solution of B2​ +​ ions, no reaction observed.
(2) Similarly, A plus C+​ ​ ions produce no reaction.
(3) When a strip of D is placed in a solution of C+​ ​ ions, black metallic C deposits on the surface
of D, and the(aq)e solution tests positively for D2​ +​ ions.
(4) When a bar of B is placed in a solution of D2​ +​ ions, metallic D appears on the surface of B
and B2​ +​ ions are found in the solution.
Arrange the ions A+​ ​, B2​ +​, C+​ ​, and D2​ +​ in order of their ability to attract electrons. On top, place
the ion that best attracts electrons