Which one of the following statements is NOT correct ?
- A.In the conduction mode of transference of heat, the molecules of solid pass heat from one molecule to another without moving from their positions
- B.The amount of heat required to raise the temperature of a substance is called its specific heat capacity
- C.The process of heat transfer in liquids and gases is through convection mode
- D.The process of heat transfer from a body at higher temperature to a body at lower temperature without heating the space between them is known as radiation
Correct answer
Explanation
The correct answer is B. Specific heat capacity is the heat needed to raise the temperature of a unit mass of a substance by one degree, not simply the heat needed to raise its temperature.
Specific heat capacity is measured in joules per kilogram per kelvin. The heat needed to raise the temperature of a whole body by one degree is its heat capacity. Heat moves in three ways: conduction, where vibrating particles of a solid pass energy to their neighbours without leaving their places; convection, where the heated fluid itself moves and carries heat, as in liquids and gases; and radiation, where energy travels as electromagnetic waves and needs no medium.
A is correct, so it is not the answer: in conduction the particles stay in place and pass energy on. C is correct, so it is not the answer: liquids and gases transfer heat mainly by convection. D is correct, so it is not the answer: radiation carries heat across space without heating it, as sunlight does.
Exam tip: specific heat is per unit mass per degree; conduction in solids, convection in fluids, radiation needs no medium.
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