Solidus Temperature is defined as the temperature at which a solid begins to melt.

Solidus Temperature is defined as the temperature at which a solid begins to melt.

• A. Temperature at which a solid begins to melt.
• B. Standard for CPVC pipe specifications.
• C. Threaded fittings made from cast bronze.
• D. Alloys with less than 0.2% lead content.

Answer: (A)

Solidus temperature is the temperature at which melting just begins. As you heat a solid, the first amount of liquid appears at the solidus; below this temperature the material is fully solid, and between the solidus and the liquidus you have a mix of solid and liquid until melting is complete at the liquidus. For a pure substance, the solidus and the melting point coincide; for alloys, there’s a two-phase region where solid and liquid coexist. The statement describing the onset of melting matches this concept exactly, so it’s the correct choice. The other options refer to pipe standards, material types, or lead content, none of which define the onset of melting.

Solidus temperature is the temperature at which melting just begins. As you heat a solid, the first amount of liquid appears at the solidus; below this temperature the material is fully solid, and between the solidus and the liquidus you have a mix of solid and liquid until melting is complete at the liquidus. For a pure substance, the solidus and the melting point coincide; for alloys, there’s a two-phase region where solid and liquid coexist.

The statement describing the onset of melting matches this concept exactly, so it’s the correct choice. The other options refer to pipe standards, material types, or lead content, none of which define the onset of melting.