Question

As per the Mohs scale of hardness, the correct sequence is

• A. Topaz > Quartz > Calcite > Talc
• B. Quartz > Topaz > Calcite > Talc
• C. Quartz > Topaz > Talc > Calcite
• D. Topaz > Calcite > Quartz > Talc

Hint:

Recall the standard order of the ten Mohs scale reference minerals, from Talc (softest) to Diamond (hardest).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept.
The Mohs scale ranks common minerals by relative hardness, from softest to hardest, using ten reference minerals. A mineral higher on the scale can scratch every mineral ranked below it.

Step 2: Key Formula or Approach.
The full Mohs scale, softest (1) to hardest (10), runs: Talc (1), Gypsum (2), Calcite (3), Fluorite (4), Apatite (5), Feldspar (6), Quartz (7), Topaz (8), Corundum (9), Diamond (10).
To rank the four minerals in this question, we just read off their standard positions on this scale.

Step 3: Detailed Explanation.
Talc sits at rank 1, the softest mineral on the scale, soft enough to be scratched by a fingernail.
Calcite sits at rank 3, still soft enough to be scratched easily by a copper coin or a knife blade.
Quartz sits at rank 7, hard enough to scratch ordinary glass and steel.
Topaz sits at rank 8, harder than quartz, and is itself scratched only by corundum or diamond.
Arranged from hardest to softest by rank number: Topaz (8) > Quartz (7) > Calcite (3) > Talc (1).

Step 4: Check the wrong options.
Option B places Quartz above Topaz, but Topaz (8) is harder than Quartz (7), so this order is reversed.
Option C swaps Talc and Calcite at the end; Calcite (3) is harder than Talc (1), so Calcite must come before Talc, not after.
Option D places Calcite above Quartz, but Calcite (3) is far softer than Quartz (7), so this order is wrong too.

Step 5: Final Answer.
The correct hardest to softest sequence is Topaz > Quartz > Calcite > Talc.
\[ \boxed{\text{Topaz} > \text{Quartz} > \text{Calcite} > \text{Talc}} \]