Which of the following statements are correct about Zn, Cd and Hg? A. They exhibit high enthalpy of atomization as the d-subshell is full. B. Zn and Cd do not show variable oxidation state while Hg shows +I and +II. C. Compounds of Zn, Cd and Hg are paramagnetic in nature. D. Zn, Cd and Hg are called soft metals. Choose the most appropriate from the options given below:
To identify the correct statements about Zn, Cd, and Hg, each option is assessed as follows:
Enthalpy of Atomization: Option A posits that Zn, Cd, and Hg have high enthalpy of atomization due to a full d-subshell. While strong metallic bonding typically leads to high enthalpy of atomization, Zn, Cd, and Hg, with their filled d-subshells and behavior akin to s-block elements, exhibit lower enthalpies of atomization compared to typical transition metals. Therefore, this statement is incorrect.
Oxidation States: Option B asserts that Zn and Cd do not display variable oxidation states, whereas Hg exhibits +I and +II oxidation states. Zn and Cd predominantly show a +II oxidation state owing to the stability of their filled d and s orbitals. Mercury can achieve +I and +II oxidation states through covalent bonding. This statement is correct.
Paramagnetic Compounds: Option C claims that compounds of Zn, Cd, and Hg are paramagnetic. These elements' compounds are generally diamagnetic, as Zn2+, Cd2+, and Hg2+ ions possess completely filled d-subshells, making them non-paramagnetic. Consequently, this statement is incorrect.
Soft Metals: Option D states that Zn, Cd, and Hg are classified as soft metals. This is accurate, with mercury being notable for its liquid state at room temperature. Thus, statement D is correct.
Based on this evaluation:
Statement B is correct because it accurately describes the oxidation behavior of Zn, Cd, and Hg.
Statement D is also correct, as it correctly identifies these elements as soft metals.
Therefore, the correct statements are B and D only.
