Question

within a water molecule: covalent bonding (intramolecular)
h-o-h
between two or more water molecules: (intermolecular force)
h₂o … h₂o … h₂o

• compounds with high intermolecular forces have high melting point, high boiling point and high viscosity.
• because of high intermolecular forces, water has a high boiling point (100 degree c) and high freezing point (0 degree c)

9a. define allotropes : an element exists in different physical forms.
9b. the different allotropes of carbon (c) are coal, graphite, diamond (is a hard substance, is used to cut glass)
and ______.

Explanation:

For part b, the different allotropes of carbon include coal, graphite, diamond, and another common allotrope is fullerene (or buckminsterfullerene, like C₆₀). Allotropes are different physical forms of the same element, and carbon's allotropes also include fullerene which has a unique molecular structure (hollow spheres, tubes, etc.).

Answer:

fullerene (or C₆₀, or buckminsterfullerene)