Question

The freezing point of water in Kelvin scale is :
A. 73.15K
B. 173.15K
C. 273.15K
D. 373.15K

Answer 1

Hint: After knowing the relation between the readings of Celsius scale and Kelvin scale, we can express the value of a particular temperature in any of these scales. We just need to find the value of $0^{\circ }$ in Kelvin scale.

Formula used: $T=t^{\circ }+273.15$

Complete step-by-step solution:
Theoretically it was found that there is a minimum temperature below which no temperature is possible. This was called the absolute zero temperature. From theoretical calculations this value was found to be around -273° C. Later experimental data suggested that the actual value of the absolute zero temperature is -273.15°C.
So, a new scale of temperature was proposed with -273.15°C as the new zero. And each division of this scale was equal to 1°C. Hence, clearly the relation is given as,
$T=t^{\circ }+273.15$
Where T is the value in Kelvin scale and t° is that in Celsius scale.
Now, the freezing point of water is t°C=0°C.
So, $T=0+273.15=273.15K$
Hence, option C is the correct answer.

Additional information:
There is another scale for measuring temperature. It is called Fahrenheit scale. If C be a temperature in Celsius scale and F be its corresponding value in the Fahrenheit scale, then,
${\displaystyle \frac{C}{5}}={\displaystyle \frac{F-32}{9}}$
However, the Kelvin scale is used widely in the field of science and technology. Because, it was found that some properties of materials are directly proportional to T or some of its powers, but not with the values obtained in Celsius or Fahrenheit scale.

Note: Keep in mind……
1. Don’t confuse the freezing point with the boiling point.
2. If the options were between 273K and 273.15 K, always choose the second one.
3. The formula is $T=t^{\circ }+273.15$. But never $T=t^{\circ }-273.15$