ICSE Class 10 Physics: Heat and Calorimetry — Important Questions with Answers 2026

Short Answer Questions (2-3 Marks)

• Q: Define specific heat capacity. State its SI unit.
  Ans: Specific heat capacity of a substance is the amount of heat required to raise the temperature of 1 kg of the substance by 1°C (or 1 K). c = Q/(mΔT). SI unit: J/(kg⋅K) or J/(kg⋅°C). Water has the highest specific heat capacity: 4200 J/(kg⋅K).
• Q: State the principle of calorimetry.
  Ans: The principle of calorimetry states: Heat lost by the hot body = Heat gained by the cold body (assuming no heat loss to surroundings). m₁c₁(T₁ - T) = m₂c₂(T - T₂), where T is the final common temperature. This is based on the law of conservation of energy.
• Q: A copper block of 200 g at 100°C is placed in 500 g of water at 20°C. Find the final temperature. (c_copper = 400 J/kg°C, c_water = 4200 J/kg°C)
  Ans: Heat lost by copper = Heat gained by water. m₁c₁(T₁ - T) = m₂c₂(T - T₂). 0.2 × 400 × (100 - T) = 0.5 × 4200 × (T - 20). 80(100 - T) = 2100(T - 20). 8000 - 80T = 2100T - 42000. 50000 = 2180T. T = 22.9°C.

Long Answer / Application Questions (4-6 Marks)

• Q: Define latent heat. Differentiate between latent heat of fusion and vaporisation.
  Ans: Latent heat is the heat energy absorbed or released during a change of state at constant temperature. Q = mL. Latent heat of fusion (Lf): heat needed to convert 1 kg of solid to liquid at melting point. For ice: 336,000 J/kg. Latent heat of vaporisation (Lv): heat needed to convert 1 kg of liquid to gas at boiling point. For water: 2,260,000 J/kg.
• Q: Why does steam at 100°C cause more severe burns than water at 100°C?
  Ans: Steam at 100°C contains additional latent heat of vaporisation (2260 kJ/kg) compared to water at 100°C. When steam touches the skin, it first releases this latent heat (2260 J/g) while condensing to water at 100°C, and then the water further releases heat while cooling. So steam transfers much more heat energy than boiling water at the same temperature.

Exam Tips for This Chapter

• Revise all definitions and laws from Heat and Calorimetry — they are commonly asked as 1-2 mark questions
• Practice diagrams related to Heat and Calorimetry — neat labelled diagrams carry 2-3 marks
• For numericals, always show formula → substitution → answer with correct units
• Previous year analysis shows Heat and Calorimetry carries 8-12 marks in the board exam