Question

The boiling point of water in Kelvin scale is:
(a). 73.15 K
(b). 173.15 K
(c). 273.15 K
(d). 373.15 K

Answer 1

- Hint: To get temperature in Kelvin scale, we have to add $$273.15$$ to the given $${}^{\circ }\text{C}$$ value.

Complete step-by-step solution -

Boiling point is the temperature required for the transformation of a liquid to the gas state. Water has a boiling point of $$100{}^{\circ }\text{C}$$. At this temperature water turns into water vapor.
To convert into the Kelvin scale, we have to add $$273.15$$ to the given $${}^{\circ }\text{C}$$ value.
Therefore, $$100{}^{\circ }\text{C = 100 + 273}\text{.15 = 373}\text{.15 K}$$
Hence the option (D) is correct.

ADDITIONAL INFORMATION:

Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid state. When the temperature increasing vapor pressure also increases, since more liquid molecules at the surface are trying to escape into the gas phase. The molecules can overcome the intermolecular forces of attraction that are prevalent in the liquid phase with the help of kinetic energy produced by the temperature. Boiling occurs when the vapor pressure above the liquid equals the atmospheric pressure. During evaporation, bubbles cannot form since the vapor pressure is less than the atmospheric pressure. While, bubbles can form during boiling since the vapor pressure can overcome the atmospheric pressure.
Boiling point mainly depends on the physical quantity such as strength of the attraction between molecules. Strong attraction between molecules will lead to the higher boiling point. Weaker attraction between molecules leads to the lower boiling point.

Note: Kelvin and Celsius scales are two different temperature measurement scales. For the physical calculations Kelvin is the most commonly used temperature measurement scale. Students are advised to learn the conversion mechanism of Celsius to Kelvin and vice versa. Fahrenheit is also used for the same purpose, but not extensively used.