Question

Which of the following scales of temperatures has only positive degrees of temperature?
A. Celsius scale
B. Fahrenheit scale
C. Reaumer scale
D. Kelvin scale

Answer 1

$- 273^\circ {\text{C}}$ is the lowest attainable temperature measured on the Celsius scale. Recall the conversion formulae to convert this temperature into the temperature scales given in the options. To get the Reaumur temperature, you have to multiply the Celsius temperature by 0.8.

Complete answer:
On the Celsius scale, we measure a wide range of temperatures from $- 273^\circ {\text{C}}$ which is the lowest attainable temperature. The temperature $- 273^\circ {\text{C}}$ is known as absolute zero temperature. Thus, we can see the temperature on the Celsius scale starts from $- 273^\circ {\text{C}}$ and increases to the positive degrees up to thousands of degrees Celsius. Therefore, the option A is incorrect.

We have the formula for conversion of Celsius temperature into Fahrenheit temperature,
${T_F} = \dfrac{9}{5}\left( {{T_C} + 32} \right)$
Here, ${T_C}$ is the temperature in Celsius scale.
If we substitute $- 273^\circ {\text{C}}$ for ${T_C}$, we get,
${T_F} = \dfrac{9}{5}\left( { - 273 + 32} \right)$
$\Rightarrow {T_F} = - 434^\circ {\text{F}}$
Thus, we can see the Fahrenheit temperature can have negative values of temperatures. Therefore, the option B is incorrect.

We have the formula for conversion of Celsius temperature into Reaumur temperature,
${T_R} = 0.8 \times {T_C}$
Thus, if the Celsius temperature is $- 273^\circ {\text{C}}$, the Reaumur scale will also have the negative value for the temperature. Therefore, the option C is incorrect.

We have the formula for conversion of Celsius temperature into Kelvin temperature,
${T_K} = {T_C} + 273$
If we substitute $- 273^\circ {\text{C}}$ for ${T_C}$, we get,
${T_K} = - 273 + 273$
$\therefore {T_K} = 0\,{\text{K}}$
Thus, we can see the Kelvin scale has the lowest temperature 0 K and always have the positive values of the temperatures.

So, the correct answer is option D.

Note: To answer this question, students must know the conversion formulae of the temperature scales. Lord Kelvin made an absolute temperature scale such that only the positive values of the temperature can be recorded. Thus, students have to add 273K into the Celsius scale to get the corresponding Kelvin temperature.