A solution is believed to contain one or more of the following ions: Cr³⁺, Zn²⁺, Fe³⁺, Ni²⁺. When the solution is treated with excess NaOH(aq), a precipitate forms. The solution in contact with the precipitate is colorless. The precipitate is dissolved in HCl(aq), and the resulting solution is treated with NH₃(aq). No precipitation occurs. Based solely on these observations, what conclusions can you draw about the ions present in the original solution? That is, which ion(s) are likely present, which are most likely not present, and about which can we not be certain? Refer to Appendix D for solubility product and complex-ion formation data.

TABLE D.1 Ground-State Electron Configurations Element Configuration Z Z 1 2 3 4 6 7 8 9 5 B 10 11 12 13 14 15 16 17 18 19 20 25 27 29 HIGMUZONSUZ SE> 0 2 3 2 3 5 3 3 4 8 5 2 30 31 He 32 Li 33 Be C F Ne Na Mg Al 21 Sc 22 Ti 23 V 24 Si P CI Ar 26 Fe K Ca 28 Ni Cr Mn Co Cu Zn Ga Ge As 34 Se 35 Br 36 Kr 1s 1s [He] 2s [He] 2s2 [He] 2s2p [He] 2s2p [He] 2s2p [He] 2s22p4 [He] 2s2p5 [He] 2s2p6 [Ne] 3s [Ne] 3s2 [Ne] 3s 3p [Ne] 3s23p 37 Rb 38 Sr 39 Y 40 Zr 41 Nb 42 Mo 43 Tc 44 Ru 45 Rh 46 Pd 47 Ag 48 Cd 49 In 50 Sn 51 Sb Te 52 53 I 54 Xe 55 Cs 56 Ba 57 La 58 Ce 59 Pr [Ar] 3d4s [Ar] 3d54s 60 Nd 61 Pm 62 Sm 63 Eu [Ar] 3d4s [Ar]3d64s [Ar]3d4s [Ar]3d845 [Ar] 3d04s [Ar] 3d04s2 64 Gd 65 Tb 66 67 [Ar] 3d04s4p Dy Ho Er 69 Tm [Ar] 3d04s4p 68 [Ar]3d04s4p [Ar] 3d04s4p4 70 Yb Lu [Ne] 3s3p [Ne] 3s23p4 [Ne] 3s 3p5 [Ne] 3s 3p6 [Ar] 4s [Ar] 4s [Ar]3d4s [Ar]3d4s [Ar]3d04s4p5 71 Element [Ar]3d04s4p6 Configuration Z [Kr] 5s [Kr] 5s [Kr] 4d5s [Kr] 4d5s [Kr] 4d45s [Kr] 4d55s [kr] 4d55s [Kr] 4d75s [Kr] 4d85s1 [Kr] 4d10 [Kr] 4d105s1 [Kr] 4d05s [Kr] 4d05s5p [Kr] 4d05s25p [Kr] 4d05s5p [kr] 4d05s25p4 [Xe] 6s [Xe] 5d6s [Xe] 4f6s [Xe] 4f6s [Xe] 4f46s2 [Xe] 4f6s2 [Xe] 4f6s2 [Xe] 4f76s2 [Xe] 4f75d6s [Xe] 4f%s2 [Xe] 4f106s2 [Xe] 4f6s NRNKERKR [Xe] 4f126s2 [Xe] 4f136s2 [Xe] 4f146s2 [Xe] 4f45d6s 72 Hf 73 Ta W 74 75 Re 76 Os 77 Element 78 79 80 81 82 83 84 85 86 87 Fr [Kr] 4d05s5p5 88 Ra [Kr] 4d05s5p6 89 Ac [Xe] 6s 90 Th 91 92 93 94 95 96 97 98 99 Ir Pt Au Hg TI Pb Bi Po At Rn Pa U Np Pu Am Cm Bk Cf Es 100 Fm 101 Md 102 No 103 Lr 104 Rf 105 Db 106 Sg Configuration [Xe] 4f45d6s [Xe] 4f145d6s [Xe] 4f145d46s2 [Xe] 4f145d56s2 [Xe] 4f145d6s2 [Xe] 4f45d6s [Xe] 4f45d6s [Xe] 4f145d106s1 [Xe] 4f145d106s2 [Xe] 4f145d6s26p* [Xe] 4f145d106s36p? [Xe] 4f145d16s?6p3 [Xe] 4f145d6s6p* [Xe] 4f145d16s26p5 [Xe] 4f145d106s26p6 [Rn] 7s [Rn] 7s [Rn] 6d7s [Rn] 6d7s [Rn] 5f26d7s [Rn] 5f6d7s [Rn] 5f46d7s2 [Rn] 5f67s [Rn] 5f77s [Rn] 5f76d7s [Rn] 5f97s2 [Rn] 5f107,2 [Rn] 5f117s2 [Rn] 5f27s [Rn] 5f137,2 [Rn] 5f147s2 Rn] 5f46d7s [Rn] 5f46d7s [Rn] 5f46d7s2 [Rn] 5f46d7s