Question

Which transition metal is liquid at room temperature?

• A. Hg
• B. Cu
• C. Ag
• D. Au
• A. Zn
• B. Cu
• C. Hg
• D. Cd
• A. Ti
• B. V
• C. Cr
• D. Mn
• A. Hf
• B. Ta
• C. W
• D. Re
• A. One
• B. Six
• C. Five
• D. Eight

Answer 1

The Correct Option is A

Mercury (Hg) is a unique transition metal, existing as a liquid at room temperature. Unlike most transition metals, which are solid due to high melting points, mercury's melting point of −38.83 °C makes it the sole liquid metal in this group at ambient conditions. This uniqueness stems from its electronic configuration, resulting in weaker metallic bonds compared to other transition metals. Consequently, mercury's state at room temperature differs from that of solid counterparts like copper (Cu), silver (Ag), and gold (Au), which possess substantially higher melting points.

Answer 2

Of the presented choices, Copper (Cu) is the hardest metal. Transition metals, as described in the passage, are characterized by their hardness and elevated melting and boiling points. This is attributed to their metallic bonding, which involves both ns and (n-1)d electrons. Copper, as a transition metal, exemplifies this characteristic. The strength of metallic bonding, and consequently the hardness and melting points of these metals, typically correlates with a greater number of d electrons involved in the bonding.

Answer 3

Transition metals generally exhibit a trend where melting points increase to a peak at the d⁵ electron configuration and subsequently decline with rising atomic number. This pattern is attributed to the growing contribution of d-electrons to metallic bonding across the series.

Manganese (Mn) deviates from this established trend. Despite possessing the d⁵ electron configuration, which typically corresponds to the highest melting point within its group, Mn does not display this characteristic. Its distinct electronic configuration influences its bonding capabilities, resulting in an exception to the general rule.

Consequently, within the scope of this inquiry, Manganese (Mn) is identified as the transition metal that does not adhere to the typical melting point maximum at the d⁵ electron configuration.

Answer 4

The transition metal with the highest melting point is identified by analyzing the general trend of melting points within a transition series. This trend indicates a peak in melting points near the middle of the d-block, frequently associated with the d5 configuration, owing to an increased number of electrons participating in metallic bonding.

Considering the provided options, Tungsten (W) exhibits one of the highest melting points among all metals. This is attributed to the strong metallic bonds formed through the contribution of its d-electrons. The melting point of Tungsten is approximately 3422°C (6192°F), positioning it as the transition metal with the highest melting point on the periodic table, exceeding that of Hafnium (Hf), Tantalum (Ta), and Rhenium (Re).

Consequently, based on melting point and bonding characteristics, the transition metal with the highest melting point is:

W (Tungsten)

Answer 5

To determine the number of electrons required for the reduction of \(Cr_{2}O_{7}^{2-}\) to \(Cr^{3+}\), we will analyze the oxidation state changes and balance the redox reaction. The steps are as follows:

1. Determine Oxidation States: In \(Cr_{2}O_{7}^{2-}\), each chromium (Cr) atom has an oxidation state of +6. In \(Cr^{3+}\), the oxidation state is +3.
2. Calculate Oxidation State Change: The reduction involves a decrease in oxidation state from +6 to +3 for each Cr atom.
3. Balance the Reduction Step: For each Cr atom, a reduction of +3 in oxidation state necessitates the gain of 3 electrons:
   

\[Cr^{6+} + 3e^- \rightarrow Cr^{3+}\]

1. Calculate Total Electrons: As \(Cr_{2}O_{7}^{2-}\) contains two Cr atoms, the total number of electrons required for the reduction is:
    

\[2 \times 3 = 6 \text{ electrons}\]

Therefore, six electrons are needed for the reduction of \(Cr_{2}O_{7}^{2-}\) to \(Cr^{3+}\).