Question

Which element from following is NOT regarded as transition element ?

• A. \(\text{Cu}\)
• B. \(\text{Sc}\)
• C. \(\text{Cd}\)
• D. \(\text{Au}\)

Hint:

A transition element has an incomplete d subshell in the atom or in its common ions; Cd has a full d10 in both.

Answer 1

The Correct Option is C

Step 1: Rule
Zn, Cd and Hg (group 12) are not counted as transition metals because their d10 shell remains full.

Step 2: Apply
Cu, Sc and Au show partly filled d subshells in the atom or in common ions ($\text{Cu}^{2+}$, $\text{Au}^{3+}$, $\text{Sc}$ atom).

Step 3: Cd
Atom $4d^{10}5s^2$, ion $4d^{10}$: always full.

Step 4: Answer
Option (C).

Final Answer:
Cd is not a transition element. This is option (C). \[ \boxed{\text{(C) }\text{Cd}} \]