Paper chromatography was used to determine if a banned preservative, X, is present in four samples obtained from four different packaged foods labelled A, B, C and D. The results of the analysis of the foodstuffs are shown in the diagram below. Which foodstuff contains X?

The diagram below illustrates the experimental set-up to carry out distillation. What are the correct labels for points A and B on the condenser?

A student performs a technique using the apparatus shown. Which separation technique has the student performed?

Rocksalt is the mineral form of sodium chloride. It is known to commonly contain sodium chloride and sand along with other trace impurities. A combination of physical changes and separation techniques can be used to produce higher purity sodium chloride and sand. What is the correct order of physical changes and separation techniques to separate sodium chloride and sand?

A substance was analysed and was found to have a boiling point of 450 °C. At room temperature it is a soft grey solid. Which temperature could be the melting point of a pure sample of the substance?

Solid P melts at exactly 60^oC and boils at exactly 310^oC. Solid Q dissolves in ethanol and shows a green colour and a yellow colour when analysed using paper chromatography. Which row is correct?

A student has performed an experiment which produced a precipitate. She correctly chooses to separate the precipitate using the process of filtration. She prepares the filter paper to be placed into the funnel by folding it as shown below. Which diagram correctly illustrates the filter paper at stage 3?

The diagram below shows the apparatus a student used to separate a product from a reaction mixture. What did the mixture contain?

A yellow solid, W is soluble in water. Which method of separation is most commonly used to obtain the solid W from an aqueous solution?

Four different dyes labelled P, Q, R and S produced the chromatograms as shown below. Which dye has an R value of 0.2?

The impure sample of paracetamol was contaminated with one of the raw chemicals used during its synthesis. What is the R_f value of the chemical?

A mixture of sugars can be separated out by paper chromatography. The student sprays the dried chromatogram with a locating agent. Why is this used?

Which row correctly describes the test for each gas?

Halide ions in solution are detected using silver nitrate solution. Dilute nitric acid is used to acidify the solution first and then a few drops of silver nitrate solution are added. Each halide produces a different coloured silver halide precipitate.

Which row correctly describes the colour of the precipitate for each halide?

A solution containing an unknown substance was analysed. On the addition of acidified silver nitrate solution a yellow precipitate formed. A flame test produced a lilac coloured flame.

What is the identity of the unknown solid?

Metal cations can be detected using flame tests.

Which row correctly describes the colour of the flame for each metal cation?

The results of two tests on a solid are shown below.

What is the solid?

Which reaction would result in the production of a gas that would produce a squeaky pop with a lit splint?

Which statement about aqueous sodium hydroxide is correct?

The results of different chemical tests on a solution of compound Y are shown.

What is compound Y?

Which statement about aqueous NaOH is correct?

Scientists test a solution of compound X. The table shows their results.

A student adds a few drops of dilute nitric acid followed by a few drops of silver nitrate solution to a test tube containing an unknown colourless solution. A white precipitate is seen. What ions could be present in the solution?

A solution containing carbonate ions can be reacted with hydrochloric acid, HCl, and a gaseous product collected and tested.

Which is a correct positive test result for a product of this reaction?