Exam code: 5070
A student noted the following observation in her laboratory notebook:
“Over several hours the particles spread from an area of high concentration to an area of low concentration. The mixture was never stirred.”
Which process is being described?
Diffusion of a substance in a liquid.
The particles of a solid during melting.
A liquid being frozen.
Diffusion of a substance through air.
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A small amount of bleach was accidentally spilled on a kitchen floor. After a while it was observed that the floor appeared to be dry and the whole kitchen smelled of bleach.
Which processes have occurred?
Evaporation and diffusion
Distillation and diffusion
Evaporation only
Diffusion only
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A student accidentally left a bottle of ammonia open in the corner of a laboratory. After a few minutes the entire laboratory smelled of ammonia.
Which process has occurred?
Dispersion
Diffusion
Evaporation
Distillation
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The diagram shows what happens when a blue soluble crystal is placed in a beaker of water.
Which row correctly describes the processes taking place?
| Chemical process | Dissolving | Diffusion |
A | |||
B | |||
C | |||
D |
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Which substance would diffuse most quickly?
carbon dioxide at 0 °C
carbon dioxide at 25 °C
neon at 0 °C
neon at 25 °C
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The rate of diffusion of two gases, methane, CH4, and propene, C3H6, is measured using the apparatus shown.
Which gas diffuses at a faster rate and why?
| Fastest gas | Reason |
A | Propene | Propene molecules are heavier and so move faster. |
B | Methane | Methane is a lighter molecule. |
C | Propene | Propene is unsaturated so is more reactive. |
D | Methane | Methane molecules are smaller so fit through the hole more easily. |
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Hydrogen chloride and ammonia are gases which are given off by cotton wool soaked in concentrated solutions and placed at either end of a glass tube as shown.
When the gases react together they produce ammonium chloride, a white solid.
Which line on the diagram correctly shows where the ammonium chloride is formed?
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The rate of diffusion of four gases, neon (Ne), hydrogen chloride (HCl), ammonia (NH3) and oxygen (O2), is measured in a sealed container.
What is the order of the rate of diffusion of the gases from slowest to fastest?
HCl → O2 → Ne → NH3
O2 → HCl → NH3 → Ne
NH3 → Ne → O2 → HCl
Ne → NH3 → HCl → O2
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