Transition metals Transitional Reasoning Practice

Questions

1. 1.

   A chemistry student investigates four unknown metallic elements, designated Q, R, T, and X, to identify which one belongs to the transition metals in Groups 3 to 12 of the periodic table. Laboratory records reveal that Q reacts vigorously with cold water to form a colorless +1 ion, R forms only a +2 ion that yields white precipitates in all reactions, and T forms a soft solid with an unusually low melting point of 98 °C. In contrast, metal X forms multiple stable chlorides with empirical formulas $XCl_2$ (blue) and $XCl_3$ (green), and it readily catalyzes the decomposition of hydrogen peroxide. Based on these characteristic observations, which element is a transition metal, and what primary evidence supports this classification?

   • A) Q, because vigorous reaction with water and formation of univalent cations define d-block metals.
   • B) R, because generating consistent +2 oxidation state compounds with white precipitates is unique to transition elements.
   • C) T, because having a low melting point and low mechanical hardness indicates incomplete d-orbital occupancy.
   • D) X, because exhibiting variable oxidation states, producing colored complex species, and demonstrating catalytic activity are typical of transition elements.

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