Recall the cation groups in classical qualitative analysis

In wet qualitative inorganic analysis, cations are separated into groups based on the reagent that precipitates them.

Group IV cations are those precipitated as sulfides by passing $H_2S$ in ammoniacal medium (or in presence of $NH_4OH/NH_4Cl$).

Common Group IV cations are: $Zn^{2+},\ Mn^{2+},\ Ni^{2+},\ Co^{2+}$

Check each option

• A: $Co^{2+}$
  $Co^{2+}$ is a Group IV cation.

• B: $Ni^{2+}$
  $Ni^{2+}$ is a Group IV cation.

• C: $Zn^{2+}$
  $Zn^{2+}$ is a Group IV cation.

• D: $Fe^{3+}$
  $Fe^{3+}$ is not in Group IV. It belongs to Group III, where cations are precipitated as hydroxides by $NH_4OH$ in presence of $NH_4Cl$.

Conclusion

The transition element cation that does not belong to Group IV is: $\boxed{Fe^{3+}}$

Comparison with stored correct answer

Stored correct answer: D
Derived answer: D ($Fe^{3+}$)

Hence, the derived answer agrees with the stored correct answer.