(i) The element that shows the maximum number of oxidation states among the elements in the 3d transition series is Chromium (Cr). Chromium can exhibit oxidation states ranging from -2 to +6. The reason for this wide range of oxidation states is due to the presence of multiple partially filled d orbitals (3d1 to 3d6). For example, chromium can form compounds in oxidation states of -2 (Cr2-), 0 (Cr^0, in elemental form), +2 (Cr2+), +3 (Cr3+), +4 (Cr4+), and +6 (Cr6+). This variety of oxidation states is a result of electron configuration changes in the 3d subshell, making Chromium highly versatile in its chemical behavior.
(ii) Among the elements listed in the 3d transition series, Tungsten (W) has the highest melting point. Tungsten has a melting point of approximately 3,422 degrees Celsius (6,192 degrees Fahrenheit). This exceptionally high melting point is due to the strong metallic bonds formed between its atoms. Tungsten's 5d and 4f orbitals contribute to its stability, allowing it to withstand extremely high temperatures.
(iii) The element that primarily shows only the +3 oxidation state among the elements in the 3d transition series is Scandium (Sc). Scandium commonly forms Sc3+ ions in its compounds. It doesn't typically exhibit other oxidation states in stable compounds.
(iv) Manganese (Mn) is a strong oxidizing agent in the +3 oxidation state. This is because Mn in its +3 oxidation state has a partially filled 3d subshell with five electrons (3d5). It is energetically favorable for Mn to lose these five electrons to achieve a stable configuration with a completely filled 3d subshell (3d10). This electron transfer from Mn3+ to other elements makes it a strong oxidizing agent, as it readily accepts electrons, oxidizing other species in the process.
