Question

$298K$ is approximately what temperature in degree Celsius?
A. ${25^o}C$
B. ${24^o}C$
C. ${29^o}C$
D. ${27^o}C$

Answer 1

Hint: Temperature is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy, present in all matter, which is the source of the occurrence of heat (a flow of energy), when a body is in contact with another that is colder. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have used various reference points and thermometric substances for definition.

Complete answer:
The most common scales are the Celsius scale (formerly called centigrade, denoted\[^\circ C\] ), the Fahrenheit scale (denoted\[^\circ F\] ), and the Kelvin scale (denoted\[K\] ), the last of which is predominantly used for scientific purposes by conventions of the International System of Units (SI).
The temperature scales are inter-related to each other and there is a certain number of divisions in each temperature scale and the upper and lower margins vary in different temperature scales. In the case of the Kelvin scale, the number of divisions is 100 and the lower margin starts from $273K$ and each division has a gap of 1 unit. Similar is the case in the Celsius scale, where the number of divisions are 100 but the lower margin starts from ${0^o}C$. Each division in the degree scale has a gap of 1 unit. Thus, the relation between degree Celsius and degree Kelvin is as follows:
$'T'kelvin = '{T^o}C' + 273$
As per the question, $'T'kelvin = 298K$
Thus, substituting this value in the above equation, we have:
$298 = 273 + {T^o}C$
Thus, the temperature in degree Celsius = ${25^o}C$

Thus option A is the correct answer.

Note:
The lowest theoretical temperature is absolute zero, at which no more thermal energy can be extracted from a body. Experimentally, it can only be approached very closely, but not reached, which is recognized in the third law of thermodynamics.