The SI base units of temperature and mass, respectively, are Select one: Celsius and milligram b. degree and gram kelvin and kilogram d. degree and kilogram
The Correct Answer and Explanation is:
The correct answer is c. kelvin and kilogram.
The International System of Units, abbreviated as SI, is the modern standard for measurement used in science, industry, and commerce worldwide. This system is built upon seven fundamental quantities, each with a precisely defined base unit. All other units, known as derived units, are formed by combinations of these seven base units.
The SI base unit for thermodynamic temperature is the kelvin (K). While the Celsius (°C) scale is commonly used in everyday life, it is considered a derived unit within the SI framework. The Celsius scale is defined relative to the kelvin scale, where a temperature difference of one degree Celsius is exactly equal to a temperature difference of one kelvin. The kelvin scale is an absolute scale, meaning its zero point, 0 K, is absolute zero. This is the theoretical temperature at which all molecular motion ceases. Because of its fundamental connection to a true physical zero, the kelvin is the standard for scientific and engineering applications. The term “degree” is not used with kelvin; it is simply called the kelvin.
The SI base unit for mass is the kilogram (kg). This is a unique case among the SI base units because it is the only one that includes a prefix, “kilo,” in its name. This is a result of historical decisions in metrology. Although units like the gram (g) and milligram (mg) are metric units of mass, they are defined as fractions of the kilogram. The gram is one-thousandth of a kilogram. For the purposes of defining the fundamental standards, the kilogram was chosen as the base unit. Therefore, when asked for the SI base unit of mass, the correct answer is always the kilogram, not the gram.
Considering both requirements, the correct pairing for the SI base units of temperature and mass, respectively, is kelvin and kilogram.
