Question

Primary standard is​

Answer 1

Answer:

A primary standard in metrology is a standard that is sufficiently accurate such that it is not calibrated by or subordinate to other standards. Primary standards are defined via other quantities like length, mass and time. Primary standards are used to calibrate other standards referred to as working standards.

Answer 2

Answer:

A primary standard is a reagent that is very pure, representative of the numbers of moles the substance contain, and easily weighed.