Mineral Hardness: Mohs Scale Ordering

The question asks to identify the correct sequence of minerals arranged in order of increasing hardness, based on the Mohs scale.

Mohs Hardness Scale Explained

The Mohs scale is a relative measure of mineral hardness, ranging from 1 (softest) to 10 (hardest). A harder mineral can scratch a softer mineral.

Analyzing Mineral Hardness Values

Let's examine the Mohs hardness values for the minerals mentioned:

Verifying the Correct Sequence

We need to find the option where the hardness values increase sequentially.

• Option C: Calcite, apatite, orthoclase, quartz
  • Calcite hardness: $3$
  • Apatite hardness: $5$
  • Orthoclase hardness: $6$
  • Quartz hardness: $7$
  The sequence of hardness is $3 < 5 < 6 < 7$. This represents increasing hardness.

Evaluating Other Options

Let's check why other options are incorrect:

• Option 1: Talc (1), Calcite (3), Gypsum (2), Apatite (5) - Incorrect because Calcite ($3$) is harder than Gypsum ($2$).
• Option 2: Orthoclase (6), Topaz (8), Quartz (7), Diamond (10) - Incorrect because Topaz ($8$) is harder than Quartz ($7$).
• Option 4: Gypsum (2), Talc (1), Calcite (3), Apatite (5) - Incorrect because Gypsum ($2$) is harder than Talc ($1$).

Therefore, the only sequence arranged correctly in order of increasing hardness is Calcite, apatite, orthoclase, and quartz.