Answer:
An unknown being weighed is hygroscopic. - operative error
One component of a mixture being analyzed quantitatively by gas chromatography reacts with the column packing. - methodic error
The tip of the pipet used in the analysis is broken. - instrumental error
In measuring the same peak heights of a chromatogram, two technicians each report different heights - operative error
Explanation:
In chemical analysis, operative errors are that largely introduced into the measurement because of variation of personal judgements of analysts. It is also a personal error that emanates solely due to the analyst.
A methodic error arises as a result of adopting defective experimental methods. For example, a column packing that reacts with a component of the mixture is used in the gas chromatography.
Instrument error refers to the error of a measuring instrument, for instance, the use of a pipette with a broken tip.
