Final answer:
Diamond is the hardest substance in the world, with a hardness value of 10 on the Mohs scale of mineral hardness.
Step-by-step explanation:
The hardest substance in the world is diamond. It is composed of carbon atoms that are tightly bonded together through a crystal lattice structure, which gives it its exceptional hardness. Diamond has a hardness value of 10 on the Mohs scale of mineral hardness.
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