Question

$ - 40^\circ C$ on absolute scale is equal to
A. 0K
B. 233K
C. 273K
D. 313K

Answer 1

Hint: The absolute scale of measuring temperature is the Kelvin scale. We can obtain temperature on the Kelvin scale by adding 273 to the temperature which is in Celsius scale. Adding this number to the given value in Celsius, we can obtain the required answer.

Complete answer:
We are given a value of temperature on the Celsius scale. It can be converted into the Kelvin scale by adding 273 to the given temperature in Celsius scale. Doing so, we get
\[ - 40^\circ C = - 40 + 273 = 233K\]
This is the required value on the absolute scale.

So, the correct answer is “Option B”.

Additional Information:
We have three scales which are used commonly for measuring temperatures. They are: Celsius scale, Fahrenheit scale and the Kelvin scale.
We encounter the Celsius scale of temperature when we are talking about the laboratory thermometer. The thermometers used to check the temperature of the human body are always calibrated in the Fahrenheit scale. These two are the most commonly used scales for measuring temperature. On the Celsius scale, the freezing point of water is $0^\circ C$ while the boiling point of water is $100^\circ C$. We can inter-convert between the Celsius scale and the Fahrenheit scale by using the following relation.
$\left( {^\circ C \times \dfrac{9}{5}} \right) + 32 = ^\circ F$
The Kelvin scale is known as the absolute scale because the lowest possible temperature on this scale is zero Kelvin. No temperature below this is possible. This scale is most commonly used in scientific regimes.

Note:
 It should be noted that in Celsius and the Kelvin scale, one degree change in temperature is the same on both scales. This is evident from the fact that we just need to add or subtract a number in order to switch between the two scales.