Property of an element by virtue of which it exists in two or more forms which differ only in their physical properties is known as allotropy. Allotropes are the different physical forms in which the element can exist. Allotropes are different physical forms of the same element.
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Allotropes are different forms of the same element in the molecular level. Isotopes are different forms of atoms of the same chemical element. The key difference between allotropes and isotopes is that allotropes are considered at the molecular level, whereas isotopes are considered at the atomic leve
