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a. "Stability of a crystal is reflected ...

a. "Stability of a crystal is reflected is reflected in the magnitude of its melting points" Comment.
b. Melting points of some compounds are given below water `= 273 K`, ethyl alcohol `= 153.7 K`, diethyl ether `= 156.8 K`, methane `= 90.5 K`. What can you say about the intermolecular forces between the molecules of these compounds?

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### Solution: **a. Stability of a crystal and its melting point:** The stability of a crystal is indeed reflected in the magnitude of its melting point. The melting point of a substance is the temperature at which it changes from a solid to a liquid. This transition occurs when the thermal energy of the particles in the solid is sufficient to overcome the intermolecular forces holding them in a fixed position. 1. **Intermolecular Forces**: The stronger the intermolecular forces (such as ionic bonds, covalent bonds, hydrogen bonds, dipole-dipole interactions, and London dispersion forces), the more energy (in the form of heat) is required to break these forces and change the solid into a liquid. Therefore, substances with strong intermolecular forces will have higher melting points. ...
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