No questions found
Which gas has the slowest rate of diffusion?
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A chromatography experiment is carried out to analyse the pigments present in four different types of leaf. The student carrying out the experiment forgot to complete his table of results, which is shown.
[Table_1]
Which row identifies the values of F, G and H?
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Which statement about isotopes is correct?
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In the chromatography experiment shown, which label represents the solvent front?
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Different methods of separation rely on substances having different properties. Which property does distillation make use of?
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The arrangements of the electrons in two ions formed from elements X and Y are shown.
Which equation represents the reaction between elements X and Y?
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Which row identifies compounds that contain single covalent bonds only, double covalent bonds only or both single and double covalent bonds?
[Table_1]
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Ethyl methanoate, HCOOC₂H₅, burns in excess oxygen to produce carbon dioxide and water.
The equation is shown.
2HCOOC₂H₅ + xO₂ \rightarrow 6CO₂ + 6H₂O
What is the value of x?
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Rubidium is in Group I of the Periodic Table and bromine is in Group VII.
Rubidium reacts with bromine to form an ionic compound.
Which row shows the electron change taking place for rubidium and the correct formula of the rubidium ion?
[Table]
| electron change | formula of ion formed |
|-----------------|-----------------------|
| A | electron gained | Rb\(^+\) |
| B | electron gained | Rb\(^-\) |
| C | electron lost | Rb\(^+\) |
| D | electron lost | Rb\(^-\) |
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Which statement explains why graphite is used as a lubricant?
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The relative atomic mass of chlorine is 35.5.
When calculating relative atomic mass, which particle is the mass of a chlorine atom compared to?
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Universal indicator solution is added to a neutral solution of concentrated aqueous sodium chloride.
The solution, which contains $H^+$ (hydrogen), $Na^+$ (sodium), $Cl^-$ (chloride) and $OH^-$ (hydroxide) ions, is electrolysed.
The product at the cathode is hydrogen gas and the product at the anode is chlorine gas.
What happens to the colour of the indicator in the solution during electrolysis?
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What is the empirical formula of an oxide of iron, formed by reacting 2.24 g of iron with 0.96 g of oxygen?
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The combustion of methane is exothermic.
$$\text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O}$$
Which statement about this reaction is correct?
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Hydrogen reacts with oxygen in a fuel cell.
$2H_2 + O_2 \rightarrow 2H_2O$
The reaction is exothermic.
286 kJ of energy is released for every mole of water formed.
Which volume of hydrogen gas, measured at room temperature and pressure, would react with oxygen with the release of 7000 J of energy?
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Which substance does not require oxygen in order to produce energy?
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Nitrogen, $N_2$, and hydrogen, $H_2$, can be converted into ammonia, $NH_3$, using a catalyst.
What is the purpose of the catalyst?
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Ammonia is produced by the Haber process. The equation is shown.
$N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$
The forward reaction is exothermic.
Which statement is correct?
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During the manufacture of sulfuric acid, sulfur dioxide is converted to sulfur trioxide.
$2SO_{2} + O_{2} \rightarrow 2SO_{3}$
Which type of reaction is this?
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The equation for a redox reaction is shown.
$$2FeSO_4 + Cl_2 + H_2SO_4 \rightarrow Fe_2(SO_4)_3 + 2HCl$$
Which element is reduced?
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The equation shows a reaction between aqueous hydrogen bromide and aqueous ammonia.
$\text{HBr(aq) + NH}_3\text{(aq)} \rightarrow \text{NH}_4^+\text{(aq)} + \text{Br}^-\text{(aq)}$
Which statement describes the role of aqueous hydrogen bromide?
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The equations for three reactions are shown.
1. $\text{Pb(NO}_3\text{)}_2\text{(aq) + 2KI(aq) } \rightarrow \text{ PbI}_2\text{(s) + 2KNO}_3\text{(aq)}$
2. $\text{2AgNO}_3\text{(aq) + CuI}_2\text{(aq) } \rightarrow \text{ Cu(NO}_3\text{)}_2\text{(aq) + 2AgI(s)}$
3. $\text{CuO(s) + H}_2\text{SO}_4\text{(aq) } \rightarrow \text{ CuSO}_4\text{(aq) + H}_2\text{O(l)}$
Which reactions are suitable for making a salt by precipitation?
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Zinc oxide is an amphoteric oxide.
Which row describes the reactions of zinc oxide?
[Table_1]
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A student carries out an experiment to prepare pure magnesium sulfate crystals.
The diagram shows the first stage of the preparation.
He adds magnesium carbonate until no more reacts.
Which process should he use for the next stage?
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Which row about elements in the Periodic Table is correct? [Table_1]
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A new element oxfordium, Ox, was discovered with the following properties.
[Table_1]
In which group of the Periodic Table should the new element be placed?
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A flammable gas needs to be removed from a tank at an industrial plant. For safety reasons, an inert gas is used. Which gas is suitable?
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Transition elements can have variable oxidation states.
Which pair of compounds shows a transition element in two different oxidation states?
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Which diagram best represents the structure of a substance that is a good conductor of electricity at 25°C?
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Why is aluminium metal unreactive with air?
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The apparatus used for the extraction of aluminium oxide by electrolysis is shown.
Which equation represents a reaction taking place at the anode?
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The results of tests on solid S and its aqueous solution are shown.
[Table_1]
What is S?
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Part of the carbon cycle is shown. What are processes P, Q and R?
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The element sulfur is found in a number of different minerals.
Which mineral contains the greatest percentage by mass of sulfur?
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Which structure represents a molecule of ethanol?
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Which structures are structural isomers of each other?
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Which molecule is not produced by an addition reaction of ethene?
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The flow chart shows the preparation of ethanol and some important chemistry of ethanol.
What are X, Y and Z?
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Which statement about nylon and Terylene is correct?
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Which diagram represents the structure of a protein?
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