Chapter Exam

Chapter-15 Experimental Techniques — Online MCQ Test

Q: In a chromatography experiment, substance A has Rf = 0.3 and substance B has Rf = 0.7 using the same solvent and paper. If a mixture of A and B is analysed, how many spots would you expect to see after development?

Answer: C. Two separate spots at positions 0.3 and 0.7 — Two separate spots will appear because each substance travels a different distance based on its unique Rf value. The different Rf values indicate they have different solubilities and will separate on the paper.

Q: An unknown gas is collected. It produces a 'pop' sound when a burning splint is inserted. When the same burning splint is held at the mouth of the test tube, it continues burning. Which gas is MOST likely present?

Answer: B. Hydrogen (H₂) — Hydrogen produces a characteristic 'pop' sound when ignited inside a test tube. When a burning splint is at the mouth of the tube, hydrogen burns with a pale blue flame, continuing to burn vigorously.

CHEMISTRY · Grade 10 · IGCSE cambridge

Practice Chapter-15 Experimental Techniques with a free chapter-wise online MCQ test for IGCSE cambridge Grade 10 CHEMISTRY. This chapter covers: Methods of separation and purification chromatography and identifying gases and ions in the laboratory.. AI-generated questions from basic to board-exam level, with instant results and explanations.

Questions

20m

Time Limit

Attempts Left

10 random questions from this chapter (mixed difficulty)
Questions you've seen before won't repeat until the pool resets
You have 20 minutes — exam auto-submits when time is up
Maximum 3 attempts per chapter
Results and explanations shown immediately after submission

New here? Register free — includes 3 free chapter exams.

Chapter-15 Experimental Techniques — Important Questions & Answers (FAQ)

Frequently asked questions from IGCSE cambridge Grade 10 CHEMISTRY — Chapter-15 Experimental Techniques, with answers and explanations. These are sample questions; the exam has its own separate question set.

What is the primary principle behind paper chromatography?

A. Separation based on density differences
B. Separation based on differential solubility and adsorption on the stationary phase ✓
C. Separation based on boiling point differences
D. Separation based on magnetic properties

Answer: B. Separation based on differential solubility and adsorption on the stationary phase
Paper chromatography separates substances based on their different rates of movement through the paper (stationary phase) when a solvent (mobile phase) carries them, determined by their solubility and adsorption properties.

In paper chromatography, what is the Rf value?

A. The ratio of solvent distance to total paper length
B. The ratio of the distance travelled by a substance to the distance travelled by the solvent front ✓
C. The ratio of the substance mass to solvent mass
D. The ratio of paper thickness to solvent concentration

Answer: B. The ratio of the distance travelled by a substance to the distance travelled by the solvent front
The Rf value (retention factor) is calculated as: Rf = distance travelled by substance / distance travelled by solvent front. It is a characteristic value for each substance in a given solvent system.

Why is a pencil line (not a pen line) used to mark the baseline in paper chromatography?

A. Pen ink dissolves in the solvent and interferes with the separation ✓
B. Pencil marks are more visible
C. Pen lines are too thick
D. Pencil is easier to erase after the experiment

Answer: A. Pen ink dissolves in the solvent and interferes with the separation
Pencil marks are used because pen ink can dissolve in the solvent and move with the mobile phase, contaminating the chromatogram and interfering with results.

In a chromatography experiment, substance A has Rf = 0.3 and substance B has Rf = 0.7 using the same solvent and paper. If a mixture of A and B is analysed, how many spots would you expect to see after development?

A. One spot at position 0.3
B. One spot at position 0.5
C. Two separate spots at positions 0.3 and 0.7 ✓
D. Three spots representing A, B, and their mixture

Answer: C. Two separate spots at positions 0.3 and 0.7
Two separate spots will appear because each substance travels a different distance based on its unique Rf value. The different Rf values indicate they have different solubilities and will separate on the paper.

An unknown gas is collected. It produces a 'pop' sound when a burning splint is inserted. When the same burning splint is held at the mouth of the test tube, it continues burning. Which gas is MOST likely present?

A. Oxygen (O₂)
B. Hydrogen (H₂) ✓
C. Carbon dioxide (CO₂)
D. Chlorine (Cl₂)

Answer: B. Hydrogen (H₂)
Hydrogen produces a characteristic 'pop' sound when ignited inside a test tube. When a burning splint is at the mouth of the tube, hydrogen burns with a pale blue flame, continuing to burn vigorously.