The correct option is **B. Specific Heat Capacity**. ### Detailed Explanation: 1. **Definition of Specific Heat Capacity**: - Specific heat capacity is defined as the amount of heat energy required to raise the temperature of 1 kilogram of a substance by 1 degree Celsius (or 1 Kelvin). It is a property that varies from one material to another and is crucial in understanding how substances respond to heat. 2. **Formula**: - The specific heat capacity (c) can be mathematically expressed using the formula: \[ Q = mc\Delta T \] where: - \( Q \) = heat energy (in joules) - \( m \) = mass of the substance (in kilograms) - \( c \) = specific heat capacity (in joules per kilogram per degree Celsius, J/kg°C) - \( \Delta T \) = change in temperature (in degrees Celsius) 3. **Understanding the Concept**: - When heat energy is added to a substance, its temperature increases. The specific heat capacity tells us how much energy is needed to achieve this temperature change. For example, water has a high specific heat capacity (approximately 4,186 J/kg°C), meaning it requires a lot of energy to increase its temperature compared to metals like iron, which have a lower specific heat capacity. 4. **Why Other Options Are Incorrect**: - **A. Thermal Conductivity**: This term refers to the ability of a material to conduct heat. It measures how quickly heat can pass through a substance, but it does not relate to the amount of heat required to change the temperature of a substance. - **C. Latent Heat**: Latent heat is the amount of heat required to change the state of a substance (e.g., from solid to liquid or liquid to gas) without changing its temperature. This is different from specific heat capacity, which deals with temperature changes within a single state of matter. - **D. Heat Transfer Coefficient**: This term describes the efficiency of heat transfer between a solid surface and a fluid (like air or water) in contact with it. It is not a measure of the heat required to change the temperature of a substance but rather how effectively heat is transferred. ### Example Calculation: Suppose we want to calculate the amount of heat required to raise the temperature of 2 kg of water from 20°C to 30°C. Using the specific heat capacity of water (4,186 J/kg°C): 1. Identify the mass \( m = 2 \) kg. 2. Identify the specific heat capacity \( c = 4,186 \) J/kg°C. 3. Calculate the change in temperature \( \Delta T = 30°C - 20°C = 10°C \). 4. Substitute into the formula: \[ Q = mc\Delta T = 2 \, \text{kg} \times 4,186 \, \text{J/kg°C} \times 10°C = 83,720 \, \text{J} \] Thus, 83,720 joules of heat energy are required to raise the temperature of 2 kg of water by 10°C. ### Common Pitfalls: - Confusing specific heat capacity with latent heat; remember that specific heat capacity deals with temperature changes, while latent heat deals with phase changes. - Not paying attention to the units; ensure that mass is in kilograms and temperature change is in degrees Celsius or Kelvin. - Misunderstanding the context of heat transfer; specific heat capacity is a property of the material itself, while thermal conductivity and heat transfer coefficient relate to how heat moves through or between materials. ### Revision Summary: - Specific heat capacity is the heat required to raise 1 kg of a substance by 1°C. - Formula: \( Q = mc\Delta T \). - High specific heat capacity means a substance can absorb a lot of heat without a significant temperature change. - Distinguish between specific heat capacity, latent heat, thermal conductivity, and heat transfer coefficient.