At the melting point of a crystalline substance, the particles which have turned liquid are moving faster than the particles which are still in the solid phase

The kinetic energies of the particles are the same. The potential energies are different; the liquid can release energy when reforming a solid.

The phase in which substances exist at typical temperatures is the phase in which they always exist.

Students find it difficult to imagine iron in the gaseous state, or mercury in the solid state. Using frozen mercury as a hammer is an effective demonstration.

Materials which are more viscous are necessarily more dense.

Cream is more viscous than milk, but less dense; it floats.

The freezing points of substances are fixed and never vary.

Freezing points depend upon several things, including prevailing pressure and the presence of dissolved solutes.

Substances are always cold when they freeze

Students would not think of molten lead as freezing when it goes from the liquid to solid state.

Ice never gets colder than 0 °C.

Ice can be cooled to near absolute zero.