Q. Which among the following statements are correct?
(1) Energy is an extensive property
(2) Specific energy is an extensive property
(3) Energy is a point function
(4) Heat capacity is an extensive property- Published on 21 Aug 15a. Statement (1), (2) and (3)
b. Statement (1), (3) and (4)
c. Statement (2), (3) and (4)
d. Statement (1), (2), (3) and (4)
ANSWER: Statement (1), (3) and (4)
We know that, when a system changes from state 1 to state 2, the change in internal energy (ΔE) of the state 2 is same as that of the state 1. Therefore value of internal energy of the system is independent of the path followed by the system. It has a fixed value along the path, therefore energy is the point function [statement (3) is correct]. But energy changes with mass of the body, therefore it is an extensive property [statement (1) is correct]. Specific energy is the energy of the system per unit mass of the system, therefore it will become intensive property [statement (2) is wrong]. Heat capacity is the product of specific heat and mass of the body. It depends on mass of the system, therefore heat capacity is an extensive property.
