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Home Questions 39BKDWT6BC
Target Exam

CUET

Subject

Chemistry

Chapter

Inorganic: D and F Block Elements

Question:

Read the passage carefully and answer the following questions.

There are mainly four series of the transition metals, 3d series (Sc to Zn), 4d series (Y to Cd), 5d series (La and Hf to Hg) and 6d series which has Ac and elements from Rf to Cn. The two series of the inner transition metals; 4f (Ce to Lu) and 5f (Th to Lr) are known as lanthanoids and actinoids respectively. Their chemical properties are transitional between those of s and p-block elements. The transition metals (with the exception of Zn, Cd and Hg) are very hard and have low volatility. Their melting and boiling points are high. Transition metals have incomplete d subshell either in neutral atom or in their ions. With partly filled d orbitals these elements exhibit certain characteristic properties such as display of a variety of oxidation states, formation of coloured ions and entering into complex formation with a variety of ligands. The transition metals and their compounds are known for their catalytic activity.

Which of the following is not regarded as transition metal?

Options:

Mercury (Hg)

Silver (Ag)

Technitium (Tc)

Scandium (Sc)

Correct Answer:

Mercury (Hg)

Explanation:

The correct answer is Option (1) → Mercury (Hg)

Based on the definition provided in the passage, the element not regarded as a transition metal is Mercury (Hg).

Why Mercury is the Answer

The passage defines transition metals as those having an incomplete d subshell either in their neutral atom state or in their ions.

  • Mercury (Hg): Along with Zinc (Zn) and Cadmium (Cd), Mercury has a completely filled d subshell ($d^{10}$) in its ground state as well as in its common oxidation states (like $Hg^{2+}$). Because it lacks the "partly filled d orbitals" mentioned in the text, it is often excluded from the strict definition of transition metals.

  • Physical Properties: The passage also notes that Zn, Cd, and Hg are exceptions to the typical hardness and low volatility of other transition metals. Mercury is a liquid at room temperature, highlighting its deviation from the group.

Comparison with Other Options

The other elements listed fit the definition of a transition metal because they have (or can form ions with) incomplete d subshells:

  • Scandium (Sc): Part of the 3d series (Sc to Zn). It has a $[Ar] 3d^1 4s^2$ configuration.

  • Technetium (Tc): Part of the 4d series (Y to Cd). It has a $[Kr] 4d^5 5s^2$ configuration.

  • Silver (Ag): Part of the 4d series. While its ground state is $4d^{10} 5s^1$, it forms $Ag^{2+}$ ions (in rare cases) with an incomplete $4d^9$ configuration, which allows it to be classified as a transition metal.

 

 

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