Material hardness (Mohs) — arrange from softer to harder: (a) Gold (b) Silver (c) Platinum (d) Diamond

Introduction / Context:
Order common precious materials by increasing hardness on the Mohs scale (approximate classroom values).

Given Data / Assumptions:

• Gold ≈ 2.5–3, Silver ≈ 2.5–3, Platinum ≈ 4–4.5, Diamond = 10.
• Where two share similar hardness (silver/gold), either may precede the other; we choose Silver then Gold.

Concept / Approach:
Rank by Mohs hardness from softer (lower) to harder (higher).

Step-by-Step Solution:
Silver (b) ~2.5–3.Gold (a) ~2.5–3.Platinum (c) ~4–4.5.Diamond (d) 10.

Verification / Alternative check:
Reference tables list diamond as the hardest; platinum harder than gold/silver.

Why Other Options Are Wrong:
They place diamond before softer metals or mix softer metals after platinum.

Common Pitfalls:
Confusing value with hardness; diamond’s price and hardness are separate properties.

Final Answer:
(b), (a), (c), (d)