Correct Answer - Option 4 : Triple point of water
Explanation:
Temperature: It is the measure of the degree of hotness and coldness of a body. The SI unit of temperature is Kelvin (K).
The major temperature scales are:
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Celsius scale: It is also known as the centigrade scale, and most commonly used scale. It is defined from assigning 0° C to 100° C of freezing and boiling point of water at 1 atmospheric pressure.
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Fahrenheit scale: The temperature scale which is based on 32° for the freezing point of water and 212° for the boiling point of water and the interval between the two range divided into 180 equal parts is called Degree Fahrenheit scale.
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Kelvin scale: It is the base unit of temperature, denoted with K. There are no negative numbers on the Kelvin scale as the lowest is 0 K.
The relation between Celsius and Kelvin is:
°C + 273.15 = K
The relation between degree Fahrenheit and degree Celsius is given by:
\(\frac{{^\circ F - 32}}{9} = \frac{{^\circ C}}{5}\)
Kelvin scale is an absolute scale and it is also known as the absolute thermodynamic scale.
Before 1954 temperature scales were based on two reference points. e.g. Degree Celsius and Fahrenheit scale.
After 1954 the scale and temperature measurement has been based on a single reference point. i.e the Tripple point of water is used as a single reference point.
According to the internationally accepted convention \(1K = ({1\over273.16})\) th of the triple point of water.