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Part of a cooling curve for water is shown. [Image_1: Cooling curve graph]
What is occurring between points X and Y?
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Which statements about clean, dry air are correct?
1. It is a mixture of elements only.
2. It is a mixture of elements and compounds.
3. It contains only non-metals.
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A representation of an atom is shown. What is the nucleon number of this atom?
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The percentage abundances of three isotopes in a sample of neon are shown. \begin{array}{|c|c|} \hline \text{isotope} & \text{percentage abundance/\%} \\ \hline {}^{20}_{10}\text{Ne} & 90.48 \\ {}^{21}_{10}\text{Ne} & 0.27 \\ {}^{22}_{10}\text{Ne} & 9.25 \\ \hline \end{array}
What is the relative atomic mass, \( A_r \), of this sample of neon?
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Potassium reacts with iodine to form potassium iodide. Which statement about potassium iodide is correct?
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Which substance has the lowest melting point?
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The diagram shows the structure of a molecule of ethyl ethanoate. What is the molecular formula of a molecule of ethyl ethanoate?
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A hydrocarbon contains 85.7\% of carbon by mass. What is the empirical formula of the hydrocarbon?
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The formula of a compound containing element X is Na$_2$X$_2$O$_3$. The relative formula mass of the compound is 158. What is the relative atomic mass of X?
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Dilute aqueous potassium chloride is electrolysed using platinum electrodes.
Which row identifies the product at each electrode? [Table_1]
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Concentrated aqueous copper(II) chloride is electrolysed using copper electrodes, as shown. What happens to the mass of each electrode during this process?
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The initial and final temperatures of four different reactions are measured. Which reaction is the least exothermic? [Table_1]
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Which equation represents an endothermic reaction?
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Methane burns in oxygen to form carbon dioxide and water. \( CH_4(g) + 2O_2(g) \rightarrow CO_2(g) + 2H_2O(l) \) The bond energies are shown. [Table_1] What is the energy change for this reaction?
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Hydrochloric acid is added to excess calcium carbonate in two separate experiments. Two different concentrations of hydrochloric acid are used but the temperature is the same in both experiments. The graph of the results shows the volume of carbon dioxide gas given off over time. Which row is correct? [Table_1]
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The decomposition of dinitrogen tetroxide, $\text{N}_2\text{O}_4$, into nitrogen dioxide, $\text{NO}_2$, is a reversible reaction. The equation for the reaction is shown.
$\text{N}_2\text{O}_4(g) \rightleftharpoons 2\text{NO}_2(g)$
The forward reaction is endothermic.
Which row shows the effect on the position of equilibrium and the rate of the reverse reaction when the temperature is increased?
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In a blast furnace, iron(III) oxide is converted to iron and carbon monoxide is converted to carbon dioxide. $$\text{Fe}_2\text{O}_3 + 3\text{CO} \rightarrow 2\text{Fe} + 3\text{CO}_2$$ What happens to each of these reactants?
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Which row describes what happens to Fe^{2+} ions when they are oxidised? [Table_1]
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In which reaction does an acid react with a base?
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Which element forms an oxide that reacts with an aqueous solution of a base?
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Which method is used to produce insoluble salts?
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The noble gases are in Group VIII of the Periodic Table. Some properties of the first four noble gases are shown. [Table_1] Which row identifies the trends in boiling point and in density as Group VIII is descended?
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Some properties of element R are shown. [Table_1] In which part of the Periodic Table is R found?
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Which pair of compounds shows that transition elements have variable oxidation states?
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The list gives the order of some metals and hydrogen in the reactivity series. Metal X is also included. most reactive K Mg Zn H X Cu least reactive Which row shows the properties of metal X? [Table_1]
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When zinc is added to an aqueous solution containing magnesium ions, there is no reaction. Which species has the greatest tendency to lose electrons?
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Which gas in the air is needed for iron to rust?
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Which coating prevents iron from rusting even when the coating is damaged?
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Why is limestone added to the blast furnace?
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The flow chart shows stages in the treatment of river water to produce drinking water. What occurs at stages J and K?
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Carbon dioxide acts as a greenhouse gas by interacting with a particular type of energy that radiates from the Earth's surface into the atmosphere. Which type of energy is involved and what happens when this energy interacts with carbon dioxide molecules? [Table_1]
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Oxides of nitrogen, such as NO and NO₂, are formed in the petrol engines of cars.
They are removed from the exhaust gases by reactions in the car’s catalytic converter.
Which row describes how oxides of nitrogen are formed in a petrol engine and a reaction that happens in the catalytic converter?
[Table_1]
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Which diagram shows the displayed formula for the named organic compound?
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What is the total number of covalent bonds in a molecule of butane, $C_4H_{10}$?
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Propane reacts with chlorine in a substitution reaction. Which reaction condition is required for the reaction to occur?
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The structure of an organic compound is shown. Which structure represents a molecule that reacts with steam to produce this product?
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Which term describes nylon?
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Ethene can be polymerised. Which diagram represents the structure of the product formed?
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An acid–base titration is described.
• 25.0 cm^3 of dilute aqueous alkali is put into a conical flask.
• Indicator is added to the flask.
• Dilute acid is added to the aqueous alkali until the indicator changes colour.
• The volume of acid used is then recorded.
Which use of apparatus is correct?
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Substance Q is investigated using chromatography. The chromatogram is shown. The diagram is not drawn to scale. What is the $R_f$ value of Q?
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