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When smoke particles are observed with a microscope they are seen to move around randomly. This is called Brownian motion.
What causes Brownian motion?
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The diagrams show four pieces of laboratory equipment: balance, pipette, stop-clock, thermometer.
Which equipment is essential to find out if dissolving a salt in water is an exothermic process?
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Iodine, I, has a lower relative atomic mass than tellurium, Te, but is placed after it in the Periodic Table.
Which statement explains why iodine is placed after tellurium in the Periodic Table?
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Which statement about the isotopes of an element is correct?
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Which two molecules contain the same number of electrons?
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Which statement describes the lattice structure of a metal?
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Which gas sample contains the most molecules?
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A student mixed together 25.0 cm^3 of 1.00 mol/dm^3 hydrochloric acid and 25.0 g of calcium carbonate.
$$2HCl(aq) + CaCO_3(s) \rightarrow CaCl_2(aq) + H_2O(l) + CO_2(g)$$
What is the maximum volume of carbon dioxide gas that could be collected at room temperature and pressure?
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Iron can react with sulfur to form two ionic compounds.
The iron is present as $\text{Fe}^{2+}$ in one compound and as $\text{Fe}^{3+}$ in the other compound.
The sulfur ion is present as $\text{S}^{2-}$ in both compounds.
What are the formulae of the two compounds?
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Aqueous copper(II) sulfate is electrolysed using carbon electrodes.
What is the product at each electrode?
[Table_1]
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The diagram shows a circuit used to electrolyse aqueous copper(II) sulfate.
Which arrows indicate the movement of the copper ions in the electrolyte and of the electrons in the external circuit?
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Methane burns in an excess of oxygen. The equation is shown.
$$ \text{CH}_4(g) + 2\text{O}_2(g) \rightarrow \text{CO}_2(g) + 2\text{H}_2\text{O}(g) $$
The bond energies are shown in the table.
[Table_1]
What is the energy change for the reaction?
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The equation for the formation of ammonia is shown.
$N_2 + 3H_2 \rightarrow 2NH_3$
The energy level diagram for the reaction is shown.
What is the energy change for the reaction?
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The effects of a change in conditions on a chemical reaction are listed.
1. The total number of collisions per minute increased.
2. The number of effective collisions per minute increased.
3. The average energy of the particles increased.
Which change in conditions caused all of these effects?
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When BiCl$_3$ reacts with water, a white precipitate of BiOCl is formed. The equation for the reaction is shown.
BiCl$_3$(aq) + H$_2$O(l) ⇌ BiOCl(s) + 2HCl(aq)
Which statements are correct?
1 The reaction is reversible.
2 When dilute hydrochloric acid is added to the reaction mixture, more of the white precipitate forms.
3 When aqueous sodium hydroxide is added to the reaction mixture, more of the white precipitate forms.
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An excess of iron(II) chloride is added to acidified potassium manganate(VII).
Which statements are correct?
1. The purple colour disappears.
2. Iron(II) is reduced to iron(III).
3. Manganate(VII) ions are oxidised to manganese(II) ions.
4. Potassium manganate(VII) is an oxidising agent.
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Part of the Periodic Table is shown.
Which element forms an oxide that reacts with dilute acid to form a salt and water?
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Aqueous sodium hydroxide is added to solid Q in a test-tube.
A gas is produced which turns damp red litmus blue.
What is Q?
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Potassium hydroxide is a base.
Which statement describes a reaction of potassium hydroxide?
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Some general rules for the solubility of salts in water are listed.
- Carbonates are insoluble (except ammonium carbonate, potassium carbonate and sodium carbonate).
- Chlorides are soluble (except lead(II) chloride and silver chloride).
- Nitrates are soluble.
- Sulfates are soluble (except barium sulfate, calcium sulfate and lead(II) sulfate).
Which substances produce an insoluble salt when aqueous solutions of them are mixed?
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Elements in Group I of the Periodic Table react with water.
Which row describes the products made in the reaction and the trend in reactivity of the elements?
[Table_1:
| | products | trend in reactivity |
|-------|--------------------------------|-------------------------------|
| A | metal hydroxide and hydrogen | less reactive down the group |
| B | metal hydroxide and hydrogen | more reactive down the group |
| C | metal oxide and hydrogen | less reactive down the group |
| D | metal oxide and hydrogen | more reactive down the group | ]
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The equation shows the reaction between a halogen and aqueous bromide ions.
$$X_2 + 2\text{Br}^- \rightarrow 2\text{X}^- + \text{Br}_2$$
......1...... ......2...... ......3......
Which words complete gaps 1, 2 and 3?
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An inert gas R is used to fill weather balloons.
Which descriptions of R are correct?
[Table_1]
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A student heated copper(II) carbonate and copper(II) nitrate in separate test-tubes. Both compounds decomposed. Which row shows the gases produced from each reaction? [Table_1]
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Metal X reacts with steam but not with cold water.
What is X?
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Which row shows uses of the metals listed? [Table_1]
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Aluminium objects do not need protection from corrosion.
Iron objects must be protected from corrosion.
Why does aluminium resist corrosion?
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Which statement describes the role of iron in the Haber process?
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Which statement about air pollutants is not correct?
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Argon is a noble gas used to fill light bulbs.
What is the approximate percentage of argon in air?
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The diagrams show experiments involving the rusting of iron.
A student predicted the following results.
1. In tube P, the iron nails rust.
2. In tube Q, the iron nails do not rust.
3. In tube R, the iron nails do not rust.
Which predictions are correct?
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A diagram of the carbon cycle is shown. Which processes are represented by the letters W, X and Y?
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Which statement about sulfur or one of its compounds is correct?
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Which reaction is endothermic?
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Which equation representing a reaction of methane is correct?
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Which two compounds are molecules which both contain a double bond?
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Ethanol can be formed by:
1. fermentation
2. reaction between steam and ethene.
Which of these processes use a catalyst?[Table_1]
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When the alcohol $\text{CH}_3\text{CH}_2\text{CH}_2\text{OH}$ reacts with the carboxylic acid $\text{CH}_3\text{CH}_2\text{CH}_2\text{COOH}$ an ester is formed.
What is the name and structural formula of this ester?
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A solution of ethanol and water is left to stand in an open beaker in a warm room for three weeks.
Which statement explains what happens to the ethanol in the solution?
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The structure of a polymer is shown. Which monomer is used to make this polymer?
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