Assertion (A) : Zinc, cadmium and mercury are not considered as transition elements.
Reason (R) : These elements have completely filled d-orbitals in their ground state as well as in their common oxidation states.
Reason (R) : These elements have completely filled d-orbitals in their ground state as well as in their common oxidation states.
Show Hint
- Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
- Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- Assertion (A) is true, but Reason (R) is false.
- Assertion (A) is false, but Reason (R) is true.
The Correct Option is A
Solution and Explanation
Let's look at Zinc (Zn), Cadmium (Cd), and Mercury (Hg):
• Zinc (\(Z=30\)): Ground state = \([\text{Ar}] 3d^{10} 4s^2 \); Ion (\(\text{Zn}^{2+}\)) = \([\text{Ar}] 3d^{10} \).
• Cadmium (\(Z=48\)): Ground state = \([\text{Kr}] 4d^{10} 5s^2 \); Ion (\(\text{Cd}^{2+}\)) = \([\text{Kr}] 4d^{10} \).
• Mercury (\(Z=80\)): Ground state = \([\text{Xe}] 5d^{10} 6s^2 \); Ion (\(\text{Hg}^{2+}\)) = \([\text{Xe}] 5d^{10} \).
In both the neutral ground state and their most common oxidation states (+2), these elements have a completely filled (\(d^{10}\)) subshell.
Step 2: Linking to the definition (Assertion).
Since transition elements must have an incomplete (partially filled) d-orbital in at least one of their common forms, Zn, Cd, and Hg fail to meet this criterion. Although they are part of the d-block, they are not transition elements. Thus, the Assertion is True.
Step 3: Conclusion.
The Reason provides the exact scientific basis for the Assertion. Hence, both are true and the Reason explains the Assertion correctly. Final Answer: (A) Both Assertion and Reason are true and Reason is the correct explanation.
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