Statement I: II B group elements are represented as only d-block elements but not transition elements

Statement II: In transition elements n, (n −1) shells are incompletely filled

Statement I and statement II are true and statement II is correct explanation of statement I

The correct answer is option 1. Statement I and statement II are true and statement II is correct explanation of statement I

Let us delve deeper into each statement and their relationship to provide a clear and detailed explanation.

Statement I: II B group elements are represented as only d-block elements but not transition elements.

The elements in Group IIB are zinc \((Zn)\), cadmium \((Cd)\), and mercury \((Hg)\). These elements have electron configurations that end in \( d^{10}s^2 \), such as:

Zinc: \([Ar] 3d^{10} 4s^2\)

Cadmium: \([Kr] 4d^{10} 5s^2\)

Mercury: \([Xe] 4f^{14} 5d^{10} 6s^2\)

These elements are part of the d-block of the periodic table because their highest energy electrons fill the d subshell. Transition elements are defined by having an incomplete d subshell either in their ground state or in one of their common oxidation states. Since the d subshells of \(Zn\), \(Cd\), and \(Hg\) are completely filled \((d^{10})\) in both their ground state and most common oxidation states, they do not meet the criteria for transition elements, which typically have partially filled d subshells.

Statement II: In transition elements, n and (n−1) shells are incompletely filled.

Transition elements are those which have an incomplete \((n-1)d\) subshell. This characteristic is what gives them their unique properties, such as variable oxidation states, the ability to form colored compounds, and paramagnetism. For transition metals, the \((n-1)d\) subshell is not completely filled, leading to electronic configurations like:

Iron (Fe): \([Ar] 3d^6 4s^2\) (incomplete 3d subshell)

Copper (Cu): \([Ar] 3d^{10} 4s^1\) (incomplete 4s subshell)

Relationship Between Statements:

Group IIB elements have a completely filled \((n-1)d^{10}\) subshell. Because the \(d\) subshell is completely filled, they do not exhibit the typical properties of transition metals, such as variable oxidation states and colored compounds, which arise from the presence of unpaired d electrons. This aligns with Statement II, which explains that having an incomplete \((n-1)d\) subshell is a defining characteristic of transition elements. Since Group \(IIB\) elements do not have this incomplete subshell, they are not considered transition elements despite being in the d-block.

Statement II explains the fundamental property that distinguishes transition metals: an incomplete \((n-1)d\) subshell. This directly explains why Group IIB elements (which have a filled \((n-1)d\) subshell) are not considered transition elements, even though they are in the d-block. The complete filling of the \((n-1)d\) subshell in Group IIB elements means they do not display the characteristic behavior of transition metals, thus fulfilling the criteria set out in Statement II.

Statement II is the correct explanation of Statement I: The reason Group IIB elements are not classified as transition elements is precisely due to the criterion described in Statement II. The filled \((n-1)d^{10}\) subshell in Group IIB elements means they lack the defining characteristic of transition elements (an incomplete \((n-1)d\) subshell).

Thus, the correct interpretation is: Statement I and Statement II are true, and Statement II is the correct explanation of Statement I.