Question

Which of the following is not an absolute temperature scale?
(A) Celsius scale
(B) Rankine Scale
(C) Kelvin Scale
(D) None of these

Answer 1

By knowing the definition of absolute temperature to choose the correct option. It is the temperature of an object on a scale where zero is taken as absolute zero. It is the lowest temperature at which the system is in a state of lowest possible energy and also there is no electronic device that can operate at this temperature .

Complete step by step answer: In the question we are asked to state which among Celsius Scale, Rankine scale and Kelvin scale is not an absolute temperature scale.
For solving this question, we must first know what is an absolute temperature scale and a few more details about the above stated scales.
So firstly, what is an absolute zero and an absolute temperature scale. Absolute zero is the temperature at which any thermodynamic system has the least or minimum energy such that no energy resulting from the molecular motion of the system can be transferred to another system. Thus, the absolute scale of temperature is the scale where the zeroth reading of the thermometer coincides with the theoretical value of the absolute zero.
A Celsius scale defines the temperature with reference to the freezing or melting point of water which is ${0^ \circ }C$ at a pressure of $1bar$ . As temperatures below ${0^ \circ }C$ are quite possible i.e. A thermodynamic system can have lowest or minimum energy at a temperature below ${0^ \circ }C$ hence a ${0^ \circ }C$ temperature in the Celsius scale does not define it to be absolute temperature. Thus, Celsius scale can not be considered as an absolute scale instead it can be called a relative scale. Thus, option A is not a correct answer to this question.
Rankine Scale is a temperature scale for which the zero of the thermometer scale coincides with the absolute zero and hence it is an absolute temperature scale. ${0^ \circ }R$ is the absolute temperature for the Rankine scale. Hence option B is a correct option.
Kelvin scale is an absolute temperature scale as a thermodynamic system has its minimum energy at $0K$temperature. Thus, at this temperature no energy transfer occurs from one system to another.

Hence, option C is a correct option to this question.

Note: A few points that we need to keep in mind are as following below:
$0K$ and ${0^ \circ }R$ are similar to each other.
Kelvin Scale is related to Celsius Scale and Rankine Scale is related to Fahrenheit Scale as change in $1K$ is same as the change in ${1^ \circ }C$ and change in ${1^ \circ }R$ is same as that of change in ${1^ \circ }F$ .
The absolute zero for Celsius scale and Fahrenheit scale are $- {273.15^ \circ }C$ and $- {459.67^ \circ }F$ respectively.