Question

Which of the following statements is not correct?
A.Volume of gas is zero at absolute zero
B.At constant pressure, volume of a gas at ${0^{\text{o}}}{\text{ C}}$ will be doubled at ${273^{\text{o}}}{\text{ C}}$
C.At constant volume, if pressure is plotted against absolute temperature, the curves are called isochores.
D.If temperature $\left( {^{\text{o}}{\text{C}}} \right)$ is doubled, the volume of gas will be doubled at constant pressure.

Answer 1

To answer this question, you must recall Charles' law. The absolute zero is the lowest temperature that can be attained in the thermodynamic temperature scale at which the enthalpy and entropy of an ideal gas reach their minimum value. Absolute zero is at the temperature zero kelvin or $- {273^{\text{o}}}{\text{C}}$.

Complete step by step solution:
As the temperature decreases with volume, at absolute zero, the volume of gas is zero.
Also since the volume increases with increase in temperature, as the temperature doubles, from $273K$ to $476K$, the volume of the gas doubles.
When volume is kept constant, it is said to be an isochoric condition. Thus, the graphs plotted at constant volume against temperature and pressure are called isochores.
We know from the ideal gas equation, that $PV = nRT$ and from Charles’ law that $\dfrac{{\text{V}}}{{\text{T}}} = {\text{ constant}}$. Thus if the temperature $\left( {^{\text{o}}{\text{C}}} \right)$ is doubled at constant pressure the volume is not doubled. As the ideal gas equation is applicable for temperature values in SI units, that is, kelvin.

Thus, the incorrect statement and answer to the problem is option D.

Note:
Charles' law gives a relation between the change in temperature of a gas with the change occurring in its volume while maintaining constant pressure. It states that the volume of a given mass of a gas varies directly with the temperature of a gas in a closed system under constant pressure conditions throughout. Thus, we can also say that, $\dfrac{{\text{V}}}{{\text{T}}} = {\text{ constant}}$.
Boyle's law gives the relation between the exerted pressure of the gas and the change occurring in its volume as a result while maintaining a constant temperature. It states that the pressure exerted by a given quantity of a gas is inversely proportional to the volume that the gas occupies under constant conditions of temperature for a closed system. Thus we can also say that, ${\text{PV = constant}}$.