AQA · GCSE Chemistry 8462

AQA GCSE Chemistry: Chemical analysis — Practice Questions & Answers

Identify pure substances, separate mixtures by chromatography, and run chemical and instrumental tests to detect gases and ions.

638 practice questions available for this topic — here are 10 with full answers and explanations.

Start an interactive quiz on Chemical analysis →

Practice questions with answers

1 Multiple choice · Easy

What is the definition of a pure substance in chemistry?

Tap an answer to check it.

WhyIn chemistry a pure substance is a single element or compound that is not mixed with any other substance.
2 Multiple choice · Easy

A formulation is best described as a mixture that has been:

Tap an answer to check it.

WhyA formulation is a useful mixture made in carefully measured quantities so that each component contributes a specific property, for example paints and fuels.
3 Multiple choice · Easy

Which gas relights a glowing splint?

Tap an answer to check it.

WhyOxygen relights a glowing splint, which is the standard test for oxygen gas.
4 Multiple choice · Easy

What is observed when carbon dioxide is bubbled through limewater?

Tap an answer to check it.

WhyCarbon dioxide turns limewater (calcium hydroxide solution) cloudy or milky white.
5 Multiple choice · Easy

In paper chromatography, what name is given to the solvent that moves up the paper?

Tap an answer to check it.

WhyThe solvent that moves through the paper is the mobile phase, while the paper itself is the stationary phase.
6 Fill in the blank · Easy

The test for hydrogen gas uses a lit splint, which produces a squeaky sound.

Answer: pop

WhyHydrogen burns rapidly with a lit splint giving a characteristic squeaky pop.
7 Multiple choice · Medium

How does damp blue litmus paper behave in the test for chlorine gas?

Tap an answer to check it.

WhyChlorine turns damp litmus paper red and then bleaches it white, because chlorine is a bleaching agent.
8 Multiple choice · Medium

Why does a pure substance melt at a specific sharp temperature, while a mixture melts over a range?

Tap an answer to check it.

WhyA pure substance has a fixed melting point, but impurities in a mixture lower and broaden the melting point into a range.
9 Multiple choice · Medium

In a chromatogram, a substance that is more attracted to the mobile phase than the stationary phase will:

Tap an answer to check it.

WhyA substance more attracted to the moving solvent (mobile phase) travels further up the paper and has a higher Rf value.
10 Multiple choice · Medium

Why must the baseline (start line) in paper chromatography be drawn in pencil rather than ink?

Tap an answer to check it.

WhyPencil is made of carbon, which is insoluble and does not dissolve in the solvent, so it will not move and interfere with the results, unlike ink.

Ready to test yourself?

Practise Chemical analysis with instant marking and per-topic score tracking.

Start the Chemical analysis quiz →

Key terms in Chemical analysis

Pure substance: A single element or compound that is not mixed with any other substance.
Pure (chemistry meaning): In science, a substance made of only one type of element or compound, which differs from the everyday meaning of clean or unadulterated.
Pure (everyday meaning): In ordinary language, a material that is natural, clean, or has had nothing harmful added, such as pure milk or pure water.
Impurity: An unwanted substance present in small amounts that is mixed with a main substance.
Mixture: Two or more substances physically combined together that are not chemically bonded.
Melting point: The temperature at which a solid turns into a liquid, used as a test for purity.
Boiling point: The temperature at which a liquid turns into a gas, used as a test for purity.
Sharp melting point: A precise temperature at which a pure substance melts, with melting and freezing points being the same value.

See the full study notes and flashcards for this topic.

Practise other AQA GCSE Chemistry topics

Topic 1: Atomic structure and the periodic table Topic 2: Bonding, structure, and the properties of matter Topic 3: Quantitative chemistry Topic 4: Chemical changes Topic 5: Energy changes Topic 6: The rate and extent of chemical change Topic 7: Organic chemistry Topic 9: Chemistry of the atmosphere Topic 10: Using resources