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MediumQ. No. what-is-the-si-unit-of-specific-heat
What is the SI unit of specific heat?
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Acal/g/°C
BJoule × kilogram⁻¹ × Kelvin⁻¹
CWatt/kg
DJoule/second
Correct Answer: Joule × kilogram⁻¹ × Kelvin⁻¹Your Answer: B
The SI unit of specific heat is derived from the basic formula c = Q/(mθ). Option A (cal/g/°C) is incorrect — this is the CGS unit of specific heat, not the SI unit. While 1 cal/g/°C = 4186 J/kg/K, the calorie-based unit is not part of the SI system. For competitive exams, it is critical to distinguish between CGS and SI units. Option B (Joule × kilogram⁻¹ × Kelvin⁻¹) is CORRECT — the SI unit of specific heat is J·kg⁻¹·K⁻¹, which can also be written as J/(kg·K) or Joule per kilogram per Kelvin. This is derived from c = Q/(mθ): [J] / ([kg] × [K]) = J·kg⁻¹·K⁻¹. This is the standard unit used in all scientific and engineering calculations. Option C (Watt/kg) is incorrect — Watt is the unit of power (J/s), not heat energy. Watt/kg does not represent specific heat. Option D (Joule/second) is incorrect — Joule/second is the unit of power (Watt), not specific heat. Specific heat involves energy per unit mass per unit temperature, not energy per unit time. For exams: SI unit of specific heat = J·kg⁻¹·K⁻¹; CGS unit = cal·g⁻¹·°C⁻¹.
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Heat is a form of energy that transfers between objects or systems due to a temperature difference, moving from a hotter body to a cooler one until thermal equilibrium is reached.
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