Question

Answer the following multiple choice questions below:

1a. Increasing the flow rate of the mobile phase would:

	A.	increase longitudinal diffusion.
	B.	affect nothing.
	C.	increase broadening due to multiple paths.
	D.	increase broadening due to mass transfer.

1b. Reverse phase HPLC of a multi-component solute usually uses:

	A .	an isocratic polar solvent.
	B.	a polar stationary phase.
	C.	a gradient from more polar to less polar solvent.
	D.	a gradient from less polar to more polar solvent.

1c. When two analytes, A and B, are passed through a chromatography column, A emerges first. We can then say:

	A.	A is less soluble than B in the mobile phase.
	B.	A is less strongly adsorbed on the stationary phase than B.
	C.	A has a larger peak area than B.
	D.	A is more strongly adsorbed on the stationary phase than B.

1d. In a given chromatographic column,

	A.	you can use a ruler to measure the plate height.
	B.	efficiency is improved by increasing plate height.
	C.	different solutes behave as if there are a different number of theoretical plates for each.
	D.	the number of theoretical plates is the same for all solutes.

1e. In a gas chromatography experiment using a non-polar stationary phase:

	A.	solutes are eluted in order of increasing polarity.
	B.	solutes are eluted in order of increasing molar mass.
	C.	solutes are eluted in order of increasing boiling point.
	D.	solutes are eluted in order of increasing vapor pressure.

Answer 1

Answer of 1a is -----B

Explanation:-- The question is belongs to reverse phase HPLC in which, when there is an increase the flow rate of mobile phase is results faster elution of analytes and give narrowed HPLC peak

Answer of 1b is -----A

Explanation:-- In reverse phase HPLC a hydrophobic stationary phse is used which works better for retention of most of organic analytes, for reverse phase HPLC of multi component solute an isocratic polar solvent is used because the mobile phase composition remains constant throughout the process and peak width is increase with retention time linearly

Answer of 1c is ----B

Explanation:-- Due to less strongly adsorbed on stationary phase it is easily separate during chromatographic separation.

Answer of 1d is ---- D

Explanation:-- The theoratical plates increase the efficiency of separation process which have hypothetical zone in which two phases such as liquid and vapour phase of substance is used to equilibrium with each other which is same for all solutes

Answer of 1e is ---- B

Explanation:-- Solutes are eluted in order to increasing molar mass because in gas chromatographic separation non polar stationary phase is generally based on molecular size and ahpe.