PH-2159
Melting, boiling and evaporation
Physics · Secondary 4 · Hard · Melting, boiling and evaporation
A block of pure wax is heated gently from room temperature. Its temperature rises until it reaches 65°C, then stays at 65°C for several minutes even though heating continues. What is happening to the wax while its temperature is constant at 65°C?
- It is melting and absorbing heat to change state while its temperature stays constant.
- It is cooling because heat is being lost to the surroundings.
- It is boiling and changing from liquid to gas throughout the wax.
- It is no longer absorbing any heat from the heater.
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