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The CORRECT choice is (b) 2 γ DM

Explanation: LONGITUDINAL diffusion is given as, B = 2 γ DM.It is ALSO called axial diffusion.

The correct answer is (a) Argon IONISATION detector

Explanation: In Argon ionisation detector, the carrier GAS is excited by a radioactive source and the atoms of carrier gas are excited to a metastable STATE. It uses argon as carrier gas.

The correct CHOICE is (b) Adsorption of GASEOUS SUBSTANCES on solid SURFACE

The BEST explanation: Gas-solid chromatography is based on the adsorption of gaseous substances on a solid surface. It is useful for the separation of rare gases.

Right answer is (C) Properties of solutes

The best explanation: Bulk PROPERTY detectors respond only to bulk properties of the MOBILE phase. It does not respond to properties of solutes.

Correct choice is (b) False

For explanation I would say: RETENTION distance is the distance between point of injection and maximum peak in the RECORDER. The CHART is drawn between time and concentration of the SOLUTE.

The correct choice is (a) True

Easiest EXPLANATION: SLOW injection of LARGE samples leads to band broadening and loss of resolution. Hence, for desired column EFFICIENCY, samples should not be too large.

The correct answer is (b) DISSOLVED in volatile liquids

The explanation is: SOLID samples must be dissolved in volatile liquids for introducing it into the COLUMN. They can be introduced directly using solid injection SYRINGES.

Right ANSWER is (a) Sulphur chemiluminescense detector

The best I can explain: In Sulphur chemiluminescense detector, the eluent is mixed with HYDROGEN and burned and then mixed with ozone and its intensity is MEASURED. The resultant is a measure of sulphur compounds PRESENT.

Correct option is (c) Leads to semi-permanent retention of the ANALYTE

To EXPLAIN I would say: Gas-solid CHROMATOGRAPHY leads to semi-permanent retention of the analyte. Hence, it is USED for limited applications.

Correct answer is (a) True

Easy EXPLANATION: The distribution coefficients of Gas-solid CHROMATOGRAPHY are GREATER than that of Gas-liquid chromatography. The stationary phase is a solid particle.

The correct option is (a) True

Easy explanation: Gas-solid chromatography can be used only for separation of certain low MOLECULAR weight GASEOUS species. This is because of gas-solid chromatography, semi-permanent RETENTION of ANALYTE only takes place.

Right answer is (a) MOLECULAR sieves

The best I can EXPLAIN: Molecular sieves are a special ADSORBENT used in gas-solid CHROMATOGRAPHY. It is used in open tubular columns.

Correct OPTION is (b) Thermionic emission detector

The explanation: Thermionic emission detector has a non-volatile bead of rubidium silicate placed above the FLAME TIP. It is maintained at about 180V with respect to the COLLECTOR.

The CORRECT option is (a) DANGEROUS to use

Explanation: Hydrogen is dangerous to use. It has BETTER THERMAL conductivity and lower density.

The CORRECT option is (a) True

The explanation: SAMPLE injection port MUST be MAINTAINED at a TEMPERATURE at which rapid vapourisation occurs but thermal degradation does not occur. The column is maintained at a different temperature.

Right choice is (d) MAXIMAL dead volume

For explanation I would say: PULSE dampers are USED to avoid variations in flow. They MUST have MINIMAL dead volume.

The CORRECT answer is (C) Refractive index detectors

To explain: Refractive index detectors depend on Snell’s law at the interface between the cell wall and the flowing liquid to deflect the LIGHT BEAM. Changes in refractive index are monitored by a POSITION sensor.

Right answer is (b) Combining RI and UV DETECTORS

Explanation: Combining RI and UV detectors almost any component can be detected. In some cases, SINGLE detection system MAY give incorrect results.

Right ANSWER is (d) QUARTZ window

Explanation: The PART that is not MARKED is quartz window. This detector is used to detect components that ABSORB any wavelength in the UV-Visible region.

Right answer is (B) HYDROGEN sulphide

To elaborate: Hydrogen sulphide cannot be RETAINED by gas-liquid columns. It can be SEPARATED using gas-solid CHROMATOGRAPHY.

Correct answer is (a) True

The explanation is: Electron capture detector is much LESS SUSCEPTIBLE to CONTAMINATION when nickel is used INSTEAD of tritium. The sensitivity of nickel is less than that of tritium.

The CORRECT choice is (b) Fluorescence DETECTORS

To explain: Fluorescence detectors can be USED for detection of AMINO acids in protein hydrolyzates by introducing the reagent dansylchloride in the sample. Other compounds that can be DETECTED are petroleum products and natural products.

The CORRECT choice is (B) Lifetime is short

The BEST I can explain: The lifetime of gas-solid chromatography is long. It can be used for geometrical ISOMERS.

Right ANSWER is (b) De-aerator

Explanation: De-aerator is used to eliminate trapper air in PUMPS of an automatic amino-acid ANALYZER. Here, bubble-trap TYPE de-aerator is used.

The correct answer is (a) PLATE number becomes greater, plate height becomes SMALLER

For EXPLANATION I would say: The efficiency of the column increases when the plate number becomes greater and the plate height becomes smaller. Column efficiency greatly DEPENDS on plate height and plate number.

Correct ANSWER is (d) SAMPLE injection SYSTEM

To explain: The UNMARKED component is syringe. Hence, the answer is sample injection system. It is for the introduction of sample into the flowing GAS stream.

Correct OPTION is (b) Cannot be used for proteins or polypeptides

The best EXPLANATION: GAS CHROMATOGRAPHY cannot be used for proteins or polypeptides. Further, accuracy is lost while CONVERTING amino-acids into the gaseous phase.