1. With gas syringes in a closed system, 200cm³ of air is passed back and forward over hot copper until the oxygen is used up. At the end, 160cm³ remains. Calculate the percentage by volume of oxygen in the air.

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2. What do each of the following state symbols represent: (s), (l), (g), (aq)

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3. Define the term Solution

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4. What percentage of the Earth's atomosphere is oxygen?

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5. State and explain how increasing temperature affects the diffusion of a gas

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6. A substance is found to melt at a single, fixed melting point. Is it likely to be a pure substance or a mixture of substances?

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7. Describe a test to show whether water is pure

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8. Define the term Solubility

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9. In paper chromatography if several dyes rise up the paper, why might another dyes not rise?

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10. When preparing hydrated copper(II) sulfate crystals starting from copper(II) oxide, why is the acid gently heated?

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11. Describe a way in which the rusting of iron could be used to show the approximate percentage of oxygen in air

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12. What observation would be made if a saturated solution is cooled?

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13. What is a base?

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14. In chromatography, what are the minimum and maximum possible values for an Rf value?

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15. In paper chromatography, why is the baseline drawn in pencil?

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16. A graph shows the solubility of sodium chloride in water at 50°C is 34g/100g. At that temperature, what mass of sodium chloride will dissolve in 50g water?

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17. For what is the separation technique of crystallisation used?

Question 17 of 17