One (or more) of the following is (are) True for the Gas Chromatography: a.Mass % of the dry gas components is measuredb.Mole % of the dry gas components is measuredc.Gasses are separated when passed through a column followed by the TCD or FID detectorsd.C, H, N, s elements are detected and the balance is oxygen element

The statements that are true for Gas Chromatography are:

b. Mole % of the dry gas components is measured: This is true. Gas chromatography is often used to determine the mole percent of the components in a mixture. This is done by comparing the area under the curve of each component in the chromatogram to the total area under the curve.

c. Gasses are separated when passed through a column followed by the TCD (Thermal Conductivity Detector) or FID (Flame Ionization Detector) detectors: This is also true. In gas chromatography, the sample is vaporized and injected onto the head of the chromatographic column. The sample is transported through the column by the flow of inert, gaseous mobile phase. The column itself contains a liquid stationary phase which is adsorbed onto the surface of an inert solid.

The other options (a and d) are not necessarily true for all gas chromatography. The detection of specific elements or the measurement of mass % would depend on the specific setup of the gas chromatography system and the detectors used.