CIE iGCSE Co-Ordinated Science C12.2 Acid-base titrations Exam Style Questions Paper 2
▶️ Answer/Explanation
Each spot’s \( R_f \) value is found using \( R_f = \dfrac{\text{distance travelled by substance}}{\text{distance travelled by solvent}} \).
Reading the chromatogram, two of the four inks (W and Y) each produce a spot that has travelled the same fractional distance up the paper, giving \( R_f = 0.7 \) for both.
The other two inks do not have a spot at this value, so only two inks contain a dye with \( R_f = 0.7 \).
✅ Answer: (C)
Reading the chromatogram, two of the four inks (W and Y) each produce a spot that has travelled the same fractional distance up the paper, giving \( R_f = 0.7 \) for both.
The other two inks do not have a spot at this value, so only two inks contain a dye with \( R_f = 0.7 \).
✅ Answer: (C)
▶️ Answer/Explanation
Chromatography separates mixtures of coloured compounds by their differing solubilities and affinities for the stationary phase.
As the solvent moves through the paper, each coloured substance travels at a different rate.
This produces separated spots or bands, allowing the components of the mixture to be identified.
✅ Answer: (A)
As the solvent moves through the paper, each coloured substance travels at a different rate.
This produces separated spots or bands, allowing the components of the mixture to be identified.
✅ Answer: (A)
▶️ Answer/Explanation
Limewater, silver nitrate, and sodium hydroxide tests each form an insoluble solid — a visible precipitate — when they react with the ion or gas being tested.
Carbonate ions reacting with dilute hydrochloric acid instead release carbon dioxide gas, with no solid precipitate forming.
This makes the carbonate/acid reaction the odd one out among the four tests.
✅ Answer: (B)
Carbonate ions reacting with dilute hydrochloric acid instead release carbon dioxide gas, with no solid precipitate forming.
This makes the carbonate/acid reaction the odd one out among the four tests.
✅ Answer: (B)