Question

Which of the following is an extensive property?
A.Heat capacity
B.Density
C.Surface tension
D.Specific heat

Answer 1

Hint:
Thermodynamics is a branch of science which deals with the study of different forms of energy and the quantitative relationship amongst them. It deals with the behaviour of the system in bulk. The properties associated with the bulk behaviour of matter are called macroscopic properties which are classified into intensive properties and extensive properties.

Step-by-step explanation:
Step 1:
Intensive property: The properties which do not depend upon the quantity of matter present in the system are called intensive property. For example: temperature does not depend upon the quantity of matter, so it is an intensive property.
Extensive property: The properties that depend upon the total matter contained in a system are defined as the extensive properties. For example: the number of moles depends upon the quantity of matter present in the solution, so it is an extensive property.
Step 2:
Heat capacity: it is a physical property of matter which is defined as the amount of heat to be supplied to a given mass of a substance to produce a unit change in its temperature. The SI unit for heat capacity is Joule/Kelvin. So, more is the given mass, greater will be the requirement of the heat to produce a unit change in its temperature. So, this is dependent on the quantity of matter present in the system. Thus, it falls in the group of extensive properties.
Step 3:
Density is defined as the mass per unit volume so is not dependent only on the mass of the system and hence is an intensive property.
Step 4:
Surface Tension is the tendency of the liquid surface to shrink into the minimum surface area possible due to the attraction of the surface layer by the bulk of the liquid. So, it is a force acting on a unit area and is not dependent on the mass of the system. So, it is an intensive property.
Step 5:
Specific heat capacity is the heat capacity of a unit mass of substance hence is not dependent on the mass of the system. So, it is an intensive property.

Hence, it is obvious that heat capacity is an extensive property and option (A) is the correct option.

Note: Students often get confused between heat capacity and specific heat capacity. Heat capacity is for the mass of the system hence an extensive property whereas specific heat capacity is for the unit mass of the system hence an intensive property.