Which one of the below statements is wrong regarding the HPLC technique? Choose one answer. Retention time for each component can be obtained High temperature is being utilized The mobile phase is a liquid Is one of the chromatography techniques

Which one of the following statement is wrong? In HPLC apparatus; Choose one answer. Internal diameter of the column determines the efficiency of the separation One of the main components is the gas reservoir Both isocratic and gradient elution can be used Mobile phase is a liquid

High-performance liquid chromatography (HPLC) uses a polar stationary phase together with a non-polar mobile phase.Which of the following molecules will have the least retention time (Rt) on HPLC? a.Molecule (II)b.Molecule (IV)c.Molecule (III)d.Molecule (I)

Select which of the following statements are true for high performance liquid chromatography (HPLC)Group of answer choicesHPLC often has an injector that only allows a fixed volume of sample (e.g. 10 μL) to be injected.There is no low-cost detector for HPLC that is as general, as sensitive, and with as large a relative range as the flame ionisation detector in gas chromatography.If the compounds in a normal phase HPLC analysis using a 50:50 vol/vol mixture of hexane: ethyl acetate were eluting too slowly, increasing the concentration of hexane would decrease the retention times of the analytes.The general elution problem in HPLC is solved by using rapid changes in temperature of the column and mobile phase.An HPLC column containing very small, uniform spherical packing material will have a higher column efficiency than a column with the particles of the same material that are larger and more irregular in size and shape.

What is chromatography used to separate?An insoluble solid from a liquidTwo or more liquids with different boiling pointsDifferent substances dissolved in a liquidTwo or more different gases2Which of the following statements about paper chromatography is not true?Less soluble substances travel further up the paperSubstances are separated based on how attracted they are to each phaseThe stationary phase is the paperThe mobile phase is the solvent3What are Rf values useful for?To determine how much solvent to use in the chromatography procedureTo calculate how much paper to useTo identify unknown samples by comparing them with known samplesTo determine the number of different substances in a solvent4How is the Rf value of a substance calculated?Distance moved by substance divided by distance moved by solventDistance moved by solvent minus distance moved by substanceDistance moved by solvent divided by distance moved by substanceDistance moved by substance multiplied by distance moved by solvent5In the core practical ‘Paper chromatography to investigate the composition of ink’, a line is drawn at the bottom of the paper onto which spots of known ink colourings plus an unknown sample are placed. There are several key points to remember when setting up this practical. Which of the following is incorrect? The line must be above the water levelThe line must be in penThe sides of the paper must not touch the beakerThe sample spots should not spread out too far6On a paper chromatogram only one spot is produced. What does this tell you? The paper was not large enoughThe substance being separated is an impure substanceToo much solvent was usedThe substance being separated is a pure substance

In which type of chromatography the stationary phase held in a narrow tubea.Liquid Chromatographyb.Paper chromatographyc.column Chromatographyd.Thin layer chromatographyClear my choice