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The diagram shows the result of dropping a purple crystal into water. Which processes take place in this experiment?
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Which row about elements, mixtures and compounds is correct? [Table_1]
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The atomic structures of four particles, W, X, Y, and Z, are shown. [Table_1]
Which particles are isotopes of the same element?
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Which statement explains why isotopes of the same element have the same chemical properties?
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Nitrogen forms a nitride ion with the formula $N^{3-}$. Which particle does not have the same electronic configuration as the nitride ion?
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Which row describes the formation of single covalent bonds in methane?
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Which formula is an empirical formula?
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Heating iron sulfide, FeS_2, in air produces sulfur dioxide. $$4 ext{FeS}_2 + 11 ext{O}_2 \rightarrow 2 ext{Fe}_2 ext{O}_3 + 8 ext{SO}_2$$ What is the maximum mass of sulfur dioxide produced from 120 kg of iron sulfide?
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Which substance produces hydrogen and bromine when electrolysed?
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Which statements about hydrogen fuel cells are correct?
1. Water is formed as the only waste product.
2. Both water and carbon dioxide are formed as waste products.
3. The overall reaction is $2H_2 + O_2 \rightarrow 2H_2O$.
4. The overall reaction is endothermic.
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Ethene gas, $C_2H_4$, is completely burned in excess oxygen to form carbon dioxide and water. The equation for this exothermic reaction is shown: $C_2H_4 + 3O_2 \rightarrow 2CO_2 + 2H_2O$ The table shows the bond energies involved in the reaction. [Table_1] What is the total energy change in this reaction?
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Which row describes the effect on the activation energy and the frequency of particle collisions when the temperature of a chemical reaction is increased? [Table_1]
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Solid copper(II) sulfate exists in two different forms, anhydrous and hydrated. One of these forms is blue and the other is white. The change between these two forms is reversible. blue form \(\rightleftharpoons\) white form What is the blue form and how is the change from the blue form to the white form brought about? [Table_1]
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Sodium ions, Na^+, and oxygen ions, O^{2-}, combine with chromium ions to form a salt. The salt sodium dichromate has the formula Na_2Cr_2O_7. What is the oxidation state of chromium in this salt?
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The concentration of hydrogen ions in 100 cm^3 of 0.1 mol/dm^3 hydrochloric acid is higher than the concentration of hydrogen ions in 100 cm^3 of 0.1 mol/dm^3 ethanoic acid. Which statement explains the difference in hydrogen ion concentration?
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Which oxide is classified as an amphoteric oxide?
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Which method produces the salt copper(II) carbonate?
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Which statements about the trends across a period of the Periodic Table are correct?
1. Aluminium is more metallic than sodium.
2. Beryllium is more metallic than carbon.
3. Boron is more metallic than lithium.
4. Magnesium is more metallic than silicon.
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Some information about elements in Group II of the Periodic Table is shown. [Table_1] Which row shows the correct trends in reactivity, density and melting point of the elements going down Group II of the Periodic Table? [Table_2]
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A new element oxfordium, Ox, was discovered with the following properties. [Table_1: solubility, electrical conduction, formula of element, bonding in a molecule of Ox_2. Values: insoluble in water, does not conduct, Ox_2, Ox≡Ox] In which group of the Periodic Table should the new element be placed?
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Which row describes a similarity and a difference between chlorine and bromine? [Table_1]
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Which statement describes transition elements?
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Which gas is made when powdered zinc is added to dilute hydrochloric acid?
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The diagram represents the structure of a solid. Which solids does the diagram represent? [Table_1]
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Steel is an alloy of iron. Which statement explains why steel is stronger than iron?
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Three students, X, Y and Z, are told that solid P reacts with dilute acids and also conducts electricity. The table shows the students' suggestions about the identity of P. [Table_1] Which students are correct?
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Which statement explains why aluminium appears to be unreactive?
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During the electrolysis of aluminium oxide, the mass of the carbon anode changes. Which row describes the change and gives a reason for this change? [Table_1]
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Several processes are used to treat domestic water. Which row identifies a reason for the given process? [Table_1]
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What is the equation for photosynthesis?
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Which statement describes how the C–H bonds in methane gas in the atmosphere contribute to global warming?
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The structural formulae of two hydrocarbons are shown. $$CH_3CH_2CH_2CH_3 \quad CH_3CH(CH_3)CH_3$$ Which statement about the hydrocarbons is correct?
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The structural formula of compound Q is given.
\[ \text{CH}_3\text{CH}_2\text{CH}_2\text{COOCH}_2\text{CH}_2\text{CH}_3 \] What is compound Q?
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The fractional distillation of petroleum is shown. Which fraction contains hydrocarbons with the longest chain length?
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Which equation represents the cracking of an alkane?
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What is the structure of the product of the reaction of propene with bromine?
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In reaction R, 2000 molecules of $\text{CH}_2=\text{CH}_2$ react to form a single molecule X only.
$$2000\ \text{CH}_2=\text{CH}_2 \rightarrow \text{X}$$
Which terms describe reaction R, $\text{CH}_2=\text{CH}_2$ and X?
[Table_1]
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Part of the structure of a polymer is shown. Which statements about the polymer are correct? 1. The polymer is nylon. 2. The polymer is formed by condensation polymerisation. 3. There are ester linkages between the monomers.
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The concentration of acids and alkalis can be determined by titration. Which pieces of equipment are needed to perform a titration?
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Which chromatogram shows how the $R_f$ value of a substance is calculated? shows four chromatograms with equations: \( R_f = \frac{y}{x} \) and \( R_f = \frac{x}{y} \).
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