Classification – Odd one out (metalloids vs noble/transition metal): Identify the outlier: Silicon, Platinum, Arsenic, Antimony.

Introduction / Context:
Chemical classification can separate metalloids from metals. Three options (Si, As, Sb) are commonly classified as metalloids; one (Pt) is a noble/transition metal.

Given Data / Assumptions:

• Silicon (Si) → metalloid.
• Arsenic (As) → metalloid.
• Antimony (Sb) → metalloid.
• Platinum (Pt) → noble/transition metal.

Concept / Approach:
Group by periodic-table category. The non-metalloid is the outlier.

Step-by-Step Solution:
Si, As, Sb → metalloids.Pt → metal (noble/transition).

Verification / Alternative check:
While classification can vary for borderline elements, Si/As/Sb are standard metalloids; Pt is unequivocally a metal.

Why Other Options Are Wrong:

• Silicon, Arsenic, Antimony share metalloid properties (semiconducting, amphoteric behavior).

Common Pitfalls:
Confusing usage (e.g., silicon in electronics) with elemental category.

Final Answer:
Platinum