Which of these images shows a pure compound?
Which is the correct description of these particles?
A mixture of compounds
A mixture of elements and compounds
A mixture of elements
A solid was heated gently. It melted at precisely 167°C. Which of these is a true statement about this substance?
It was diamond
It was a pure substance
It was a mixture of two substances
What is the name of a mixture which has been designed as a useful product?
Cosmetic
Formulation
Emulsion
Which method is usually used to separate and identify coloured dyes from each other?
Chromatography
Simple distillation
Crystallisation
During paper chromatography to separate different pigments from a mixture, using water as the solvent, what is the stationary phase?
The paper
The water
The pigments
How can you tell from a chromatogram how many substances were present in the mixture?
Measure the height of each of the spots and add the distances together
Count the number of spots made from the original mixture
Calculate the Rf value and compare it to the value from a data book
Where are the spots of the samples placed in chromatography?
Randomly on the piece of paper
In a vertical line on the paper
In a horizontal line on the paper
A gas is tested with a burning splint and produces a squeaky pop. What gas is it?
Oxygen
Carbon dioxide
Hydrogen
Which gas causes damp blue litmus paper to turn white?
Chlorine