Which of the following materials is usually regarded as the hardest substance available on Earth?

Options :
  1. Platinum
  2. Coal
  3. Diamond
  4. Gold

Answer and Explanation :-

Answer: Option 3


Diamond is the hardest known natural material on the Mohs scale of mineral hardness, where hardness is defined as resistance to scratching and is graded between 1 (softest) and 10 (hardest). Diamond has a hardness of 10 (hardest) on this scale. Diamond's hardness has been known since antiquity, and is the source of its name.

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