iGCSE Chemistry Multiple Choice (Extended) : 12.3 Chromatography: Exam Style Questions Paper 2

Question

The diagram shows the structure of a naturally occurring polymer, Q.

What is Q?

A) an amino acid
B) nylon
C) a protein
D) PET

▶️ Answer/Explanation

Solution

Ans: C

The structure shown represents the peptide bond (-CO-NH-) that links amino acids together in proteins.

Option A is incorrect because an amino acid is a monomer, not a polymer.

Option B (nylon) is incorrect because while nylon does contain similar amide linkages, it is synthetic, not naturally occurring.

Option D (PET) is incorrect as it contains ester linkages, not amide linkages.

Proteins are natural polymers formed from amino acids through condensation reactions, creating peptide bonds as shown in the diagram.

Question

The chromatogram of substance S is shown.

Some distances, W, X, Y and Z, are labelled on the diagram.

How is the R_f value of substance S calculated?

A \(\frac{X}{Y}\)
B \(\frac{W}{Z}\)
C \(\frac{Y}{X}\)
D \(\frac{Y}{W}\)

▶️ Answer/Explanation

Solution

Ans: C

The R_f (retention factor) value in chromatography is calculated as:

\[ R_f = \frac{\text{distance traveled by substance}}{\text{distance traveled by solvent front}} \]

From the diagram:

– Y represents the distance traveled by the substance from the baseline

– X represents the distance traveled by the solvent front from the baseline

Therefore, the correct calculation is \(\frac{Y}{X}\), which corresponds to option C.

W and Z distances are not relevant for calculating R_f values as they don’t represent the key movement measurements needed.

Question

Two different food colourings, X and Y, are tested using chromatography.
Three pure dyes, 1, 2 and 3, are also tested.
The chromatogram is shown.

Which statements are correct?
1 X and Y both contain two or more dyes.
2 Dyes 2 and 3 are present in both X and Y.
3 The Rf of dye 1 is 0.625.
A 1 and 2 only B 1 and 3 only C 1, 2 and 3 D 2 and 3 only

Answer/Explanation

Ans: C

Question

Which statement about paper chromatography is correct?
A A solvent is needed to dissolve the paper.
B Paper chromatography separates mixtures of solvents.
C The solvent should cover the baseline.
D The baseline should be drawn in pencil.

Answer/Explanation

Ans: D

iGCSE Chemistry Multiple Choice (Extended) : 12.3 Chromatography: Exam Style Questions Paper 2

Question

Question

Resources

Members

Company