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⚛️ Physics  ·  Thermal Properties of Matter  ·  NEET & JEE

The heat needed to change the state of a substance at constant temperature is called the:

Answer: latent heat.

  • A latent heat
  • B specific heat
  • C sensible heat
  • D molar heat

Correct answer: A. latent heat

Explanation: Latent heat drives a phase change without a temperature change.

Heating Curve: Ice → Water → SteamHeat added (Q)T (°C)ice warms (-ve→0°C)melting (0°C, latent heat)water warms (0→100°C)boiling (100°C, latent heat)FLAT regions = phase change (all heat goes into breaking bonds, NOT raising temperature)

During a phase change (melting or boiling), temperature stays constant while heat is absorbed entirely as latent heat (Q=mL); temperature only rises again once the substance is fully in its new phase.

Concept context

Temperature scales, thermal expansion, calorimetry, and the three modes of heat transfer including radiation laws.

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