20. Which of the below statement is incorrect for the isothermal compressibility?
(A) can be obtained from the slope of the plot of volume against pressure at constant temperature
(B) for ideal gas, the isothermal compressibility is inversely proportional to pressure
(C) The higher the pressure of the gas, the lower its compressibility
(D) is a measure of the fractional change in volume when the pressure is increased by a small amount at constant temperature
(E) none of the above answer is incorrect