Least count of a spectrometer depends on the device that you have, normally in labs , the least count is 0.01mm or 0.001cm least count = pitch / number of divisions on the circular scale head normally number of divisions on circular scale head is 100 and pitch is 1mm (i.e. on the linear scale) so least count = 1 / 100 …

Figure 12.4.1 shows an example of a typical gas chromatograph, which consists of several key components: a supply of compressed gas for the mobile phase; a heated injector, which rapidly volatilizes the components in a liquid sample; a column, which is placed within an oven whose temperature we can control during the separation; and a detector.