10th Sep '25

Multiple Choice 2015-16

Question	Answer	Point
What is a 'pure substance'?	the concept of a pure substance	A pure substance contains only what it is labelled as. It is not contaminated with something unexpected eg food grade chemicals.
What is a trace substance?	A trace substance is chemical found in very small amounts. These may make substances impure.	A trace substance is chemical found in very small amounts. These may make substances impure.
How can we identify a pure substance from an impure?	the identification of pure substances	Pure substances can be identified by being unable to separate them.
How can we separate salt from sand?	simple techniques for separating mixtures: filtration, evaporation, distillation and chromatography	To be able to describe simple techniques for separating mixtures: filtration, evaporation.
What is filtration?	Filtration separates by size of particle, normally solid and liquid.	Filtration separates by size of particle, normally solid and liquid.
What is a residue?	The solid left behind in the filter is called the residue.	The solid left behind in the filter is called the residue.
What is a filtrate?	The liquid that has passed through the filter is called the filtrate.	The liquid that has passed through the filter is called the filtrate.
What allows us to separate substances through evaporation?	Evaporation separates by differences in boiling point, collecting the substance with the higher point.	Evaporation separates by differences in boiling point, collecting the substance with the higher point.
What is distillation?	To be able to describe simple techniques for separating mixtures: Distillation.	To be able to describe simple techniques for separating mixtures: Distillation.
How does distillation work?	Distillation separates by differences in boiling point, collecting the substance with the lower point.	Distillation separates by differences in boiling point, collecting the substance with the lower point.
What is chromatography?	To be able to describe simple techniques for separating mixtures: chromotography.	To be able to describe simple techniques for separating mixtures: chromotography.
Why would we use chromatography to identify a type of sweet?	Chromatography can be used to separate mixtures of coloured compounds.	Chromatography can be used to separate mixtures of coloured compounds.
What does soluble mean?	If a solid can dissolve in particular liquid then it is know as 'soluble'.	If a solid can dissolve in particular liquid then it is know as 'soluble'.
What does insoluble mean?	If a solid cannot dissolve in particular liquid then it is know as 'insoluble'	If a solid cannot dissolve in particular liquid then it is know as 'insoluble'
What is a solution?	Solutions are mixtures of solids and liquids, in which the solid breaks down and behaves like a liquid.	Solutions are mixtures of solids and liquids, in which the solid breaks down and behaves like a liquid.
What is the solid that dissolves in a liquid called?	The solid added is called the solute.	The solid added is called the solute.
What is the liquid a solid dissolves into called?	The liquid added is called the solvent.	The liquid added is called the solvent.
What happens to the solute particles when they dissolve?	The large solute (solid) crystal break down into smaller molecules which fit between the particles of the solvent.	The large solute (solid) crystal break down into smaller molecules which fit between the particles of the solvent.
How do the particles behave once they have dissolved?	The solid can now behave like a liquid as the small molecules can move relative to each other.	The solid can now behave like a liquid as the small molecules can move relative to each other.
What does it mean when a solution is saturated?	A saturated solution is one that can not dissolve any more solute.	A saturated solution is one that can not dissolve any more solute.
In terms of particles, why does a solution become saturated?	When all the gaps between particles are full, no more solute can be dissolved.	When all the gaps between particles are full, no more solute can be dissolved.
Why does increasing the temperature increase the amount of solute that can dissolve?	Increasing the temperature of the solvent, increases the speed the particles collide, creating bigger gaps. This allows more solute to dissolve in the solvent.	Increasing the temperature of the solvent, increases the speed the particles collide, creating bigger gaps. This allows more solute to dissolve in the solvent.
What is solubility?	Solubility is a measure of how much solute can be dissolved in a solvent.	Solubility is a measure of how much solute can be dissolved in a solvent.
What is concentration?	Concentration is the number of a particular type of particle in a volume of space.	Concentration is the number of a particular type of particle in a volume of space.
What is diffusion?	diffusion in liquids and gases driven by differences in concentration	Diffusion is the movement of a substance from a region of higher concentration to a region of lower concentration.
What happens to the particles in a fluid?	diffusion in terms of the particle model	Particles in a fluid are always moving.
Why do particles move from an area where there are more to where ther	Half of a large number is more than half of a smaller number. So more particles will travel from a larger number of particles (high concentration), than are replaced by the smaller number moving form the smaller number of particles (lower concentration).	Half of a large number is more than half of a smaller number. So more particles will travel from a larger number of particles (high concentration), than are replaced by the smaller number moving form the smaller number of particles (lower concentration).

Mod	Number of Questions
0S	10
1B	10
1C	10
1P	10
BI	5