May/June 2023

Element X contains six more protons than element Y. Which statement has to be correct?

Atomic structure

Which of the following statements is correct?

Atoms, molecules and stoichiometry

Iodine and propanone react in line with the equation below: $\text{I}_2(aq) + \text{CH}_3\text{COCH}_3(aq) \rightarrow \text{CH}_3\text{COCH}_2\text{I}(aq) + \text{HI}(aq)$. When the concentration of propanone is raised while the total reaction volume is kept unchanged, the initial rate of the reaction also rises. What might account for this?

Reaction kinetics

Four consecutive ionisation energies (IE) for element E are given. Element E belongs to Period 3 of the Periodic Table. The fifth IE is $16000\ \text{kJ mol}^{-1}$, the sixth IE is $20000\ \text{kJ mol}^{-1}$, the seventh IE is $24000\ \text{kJ mol}^{-1}$ and the eighth IE is $29000\ \text{kJ mol}^{-1}$. E is in which group of the Periodic Table?

The Periodic Table: chemical periodicity

For this question, take the gas produced to behave as an ideal gas. A $1.7\ \text{g}$ sample of $\text{Mg}$ reacts with $50.0\ \text{cm}^3$ of $2.2\ \text{mol dm}^{-3}\ \text{HCl}$ at $303\ \text{K}$ and $110\,400\ \text{Pa}$. What volume of gas is formed when measured under these conditions?

Atoms, molecules and stoichiometry

When chlorine dioxide, $\text{ClO}_2$, reacts with aqueous sodium hydroxide, it forms water together with a mixture of two sodium salts, $\text{NaClO}_2$ and $\text{NaClO}_3$. What is the mole ratio of $\text{NaClO}_2$ to $\text{NaClO}_3$ in the product mixture?

Atoms, molecules and stoichiometry

The temperature of a sample of an inert gas is raised. How does this change the number of molecules with the most probable energy and the number of molecules with higher energy?

States of matter

Which compound shows the largest percentage decrease in mass when heated strongly?

Analytical techniques

At room temperature, the solid compounds sodium chloride and sodium iodide each undergo reaction with concentrated sulfuric acid. For $\text{NaCl}$, the products formed are $\text{NaHSO}_4$ and $\text{HCl}$. For $\text{NaI}$, the products formed are $\text{NaHSO}_4$, $\text{HI}$, $\text{I}_2$, $\text{SO}_2$, $\text{H}_2\text{O}$, $\text{S}$ and $\text{H}_2\text{S}$. What explains this difference in products?

Electrochemistry

The melting point of $\text{SiO}_2$ is $1713\ ^\circ\text{C}$. In the presence of hot $\text{NaOH}(aq)$, it reacts to produce sodium silicate, $\text{Na}_2\text{SiO}_3$, as well as water. However, when $\text{SiO}_2$ is added to hot $\text{H}_2\text{SO}_4(aq)$, there is no reaction. What can be inferred from this information?

The Periodic Table: chemical periodicity

Element X has the second-largest atomic radius within its period. A neutral atom of X contains only three occupied electron shells. The oxide of X is mixed with water by shaking. What might be the $\text{pH}$ of the solution formed?

The Periodic Table: chemical periodicity

Which statement accounts for calcium having a higher melting point than barium?

Group 2

Which exhaust gas from an internal combustion engine causes marble statues to wear away?

Nitrogen and sulfur

The diagram displays the melting points of eight elements whose atomic numbers are consecutive. Which element might be sodium?

The Periodic Table: chemical periodicity

The boiling points of $\text{Br}_2$, ICl and IBr are shown in the table. The boiling point / $^\circ\text{C}$ values are: $\text{Br}_2$: 59, ICl: 97, IBr: 116. Which row gives the explanation for: • why ICl has a higher boiling point than $\text{Br}_2$ • why IBr has a higher boiling point than ICl?

Chemical bonding

An aqueous mixture includes both $\text{Mg}^{2+}$(aq) and $\text{Sr}^{2+}$(aq) at the same concentration. The mixture is split into two equal parts. Aqueous sodium hydroxide is then added drop by drop to one part. Dilute sulfuric acid is then added drop by drop to the other part. Which row is the correct one?

Equilibria

When working through this question, take account of structural isomerism and stereoisomerism. Where a molecule has two non-identical chiral carbon atoms, there are four optical isomers. Determine the number of isomers that have: • molecular formula $\text{C}_7\text{H}_{14}\text{O}$ and • a five-membered ring and • a tertiary alcohol group?

Hydroxy compounds

Which reagent reacts with pentan-3-ol to form a mixture of stereoisomers?

Hydroxy compounds

An organic molecule W has 3 carbon atoms. It needs 4.5 molecules of oxygen for complete combustion. What could W be?

Atoms, molecules and stoichiometry

Which equation shows a reaction that occurs by initiation, propagation, and termination steps?

Reaction kinetics

When answering this question, take both structural isomerism and stereoisomerism into account. A collection of isomeric hydrocarbons: • each one contains 14.3% by mass of hydrogen • each one undergoes addition with bromine, with 0.280 g of every hydrocarbon reacting with 0.799 g of bromine. What is the greatest possible number of isomeric compounds in the collection?

Atoms, molecules and stoichiometry

Which row states the solvent employed and the kind of reaction taking place when bromoethane reacts with NaOH to make ethene?

Halogen compounds

Three statements concerning potassium, chlorine and their ions are given below. Which of these statements is correct?

Chemical bonding

Which row shows the kind of reaction that takes place when propan-1-ol reacts to form the carbon-containing product named?

Hydroxy compounds

Which statement explains the change that occurs when 2-chloro-2-methylpropane is warmed with NaOH(aq)?

Halogen compounds

How many structural isomers of secondary alcohols are there for the molecular formula $\text{C}_5\text{H}_{12}\text{O}$?

Hydroxy compounds

Which reagent: • is able to confirm that an organic compound contains a carbonyl group • cannot tell aldehydes from ketones?

Carbonyl compounds

Which compound gives a positive result with alkaline aqueous iodine and does not display optical isomerism?

Carbonyl compounds

Two separate samples of compound X were each reacted with different reagents, and each reagent was added in excess. The products formed in these two reactions are shown. Which reagents might be used for reaction 1 and reaction 2?

Organic synthesis

What method could be used to produce butanoic acid?

Carboxylic acids and derivatives

Which ester can be hydrolysed to yield two products, one of which can be reduced to form the other?

Carboxylic acids and derivatives

Compounds X and Y are combined, and a small quantity of concentrated $\text{H}_2\text{SO}_4$ is then added. In the product mixture formed, ester Z is detected. Which pair of compounds might X and Y be?

Carboxylic acids and derivatives

The diagram represents part of a polymer molecule. $-\text{CH}_2-\text{CH=CH}-\text{CH}_2-\text{CH}_2-\text{CH=CH}-\text{CH}_2-$ Which monomer would form this polymer?

Chemical bonding

In which equilibrium are both equilibrium constants $K_c$ and $K_p$ unitless?

Equilibria

Bromine has two isotopes that occur naturally. One isotope contains 44 neutrons, and the other contains 46 neutrons. If fragments are ignored, how many peaks would be observed in the mass spectrum of tribromomethane, $^{12}\text{C}^1\text{HBr}_3$?

Analytical techniques

Calcium carbide, $\text{CaC}_2$, reacts with water, as illustrated. The information below the equation gives, in $\text{kJ mol}^{-1}$, the standard enthalpies of formation for the compounds taking part. $\text{CaC}_2(s) + \text{H}_2\text{O}(l) \rightarrow \text{CaO}(s) + \text{C}_2\text{H}_2(g)$ What is the standard enthalpy change for the reaction shown?

Chemical energetics

In the sodium chloride lattice, the number of chloride ions surrounding each sodium ion is called the coordination number of the sodium ions. What are the coordination numbers for the sodium ions and the chloride ions in the sodium chloride lattice?

Chemical bonding

Histidine is an amino acid. What are the approximate bond angles 1, 2, and 3?

Chemical bonding

The Contact process is carried out at a pressure in the range $100\ 000\ \text{Pa}$ to $200\ 000\ \text{Pa}$. A catalyst is employed. Which statement is correct?

Equilibria

At $25\ ^\circ\text{C}$, bromine undergoes reaction with aqueous sodium hydroxide. Reaction 1: $\text{Br}_2(aq) + 2\text{NaOH}(aq) \rightarrow \text{NaBr}(aq) + \text{NaOBr}(aq) + \text{H}_2\text{O}(l)$. The $\text{NaOBr}$ produced is unstable at $25\ ^\circ\text{C}$ and reacts further. Reaction 2: $3\text{NaOBr}(aq) \rightarrow 2\text{NaBr}(aq) + \text{NaBrO}_3(aq)$. Which reactions are disproportionation reactions?

Electrochemistry

During analysis of chlorine gas using a mass spectrometer, $^{35}\text{Cl}^+$ ions are detected. Which row is correct?

Atomic structure

Nitrogen monoxide is quickly oxidised to nitrogen dioxide. $2\text{NO}(g) + \text{O}_2(g) \rightarrow 2\text{NO}_2(g)$ Nitrogen dioxide may then dimerise to give dinitrogen tetroxide. $2\text{NO}_2(g) \rightarrow \text{N}_2\text{O}_4(g) \quad \Delta H^{\circ} = -58\,\text{kJ mol}^{-1}$ $\Delta H_f^{\circ}(\text{NO}) = +91\,\text{kJ mol}^{-1}$ and $\Delta H_f^{\circ}(\text{NO}_2) = +34\,\text{kJ mol}^{-1}$ What is the value of the standard enthalpy change for the reaction shown? $2\text{NO}(g) + \text{O}_2(g) \rightarrow \text{N}_2\text{O}_4(g)$

Chemical energetics

$\text{LiAlH}_4$ has $\text{AlH}_4^-$ ions, in which aluminium is in oxidation state $+3$. $\text{LiAlH}_4$ reacts with water, as follows. $\text{LiAlH}_4 + 4\text{H}_2\text{O} \rightarrow 4\text{H}_2 + \text{LiOH} + \text{Al(OH)}_3$ In this reaction, each of the four water molecules forms one hydroxide ion. This happens by losing one $\text{H}^+$ ion, which then reacts with the $\text{LiAlH}_4$. Which changes in oxidation number take place in this reaction?

Electrochemistry

The vanadium salt, $\text{VOSO}_4$, dissolves in water and is very reactive with powdered manganese in dilute sulfuric acid. The reaction equation is given below. $\text{Mn}(s) + 2\text{VOSO}_4(aq) + 2\text{H}_2\text{SO}_4(aq) \rightarrow \text{V}_2(\text{SO}_4)_3(aq) + \text{MnSO}_4(aq) + 2\text{H}_2\text{O}(l)$ Which statement correctly describes this reaction?

Electrochemistry

For which equilibrium will raising the pressure while keeping the temperature constant increase the yield of the products on the right-hand side of the equation?

Equilibria

Hydrogen iodide is placed in a reaction vessel from which the air has been removed. The vessel is then sealed and heated. Decomposition takes place, producing hydrogen and iodine. A quantity of hydrogen iodide is still present. Once equilibrium has been reached, the total pressure is $1.20 \times 10^5\,\text{Pa}$. The partial pressure of hydrogen is $4.00 \times 10^3\,\text{Pa}$. Under the conditions used, hydrogen iodide, hydrogen and iodine are all in the gaseous state. Calculate the value of $K_p$ for the equilibrium at this temperature, assuming the decomposition is the forward reaction.

Equilibria

The following equations represent two reactions. reaction X: $2\text{NOBr} \rightarrow 2\text{NO} + \text{Br}_2$ reaction Y: $2\text{NOCl} \rightarrow 2\text{NO} + \text{Cl}_2$ These two reactions proceed by similar mechanisms. When temperature, pressure and reactant concentration are all the same, the starting rate of reaction X is higher than the starting rate of reaction Y. Which statements account for this difference?

Reaction kinetics

The diagram illustrates the Boltzmann distribution for the energies of particles in a gas. This gas may undergo a reaction with an activation energy, $E_a$. The gas is kept at a fixed temperature. Which of the statements is correct?

Reaction kinetics

L, M and N are three distinct elements from Period 3 of the Periodic Table. L is the element whose atoms contain three unpaired electrons in its $3p$ sub-shell. M is the element that has the greatest electrical conductivity in the period. N is the element with the greatest melting point in the period. Which statement about element L is correct?

The Periodic Table: chemical periodicity

For reactions 1 and 2, X stands for an element in Period 3. In both reactions, X is being converted into a product in which X has its maximum oxidation state. reaction 1: chlorine + element X $\rightarrow X_y\text{Cl}_z$ reaction 2: oxygen + element X $\rightarrow X_p\text{O}_q$ Which ratios increase progressively from sodium to phosphorus?

The Periodic Table: chemical periodicity

Sodium, magnesium, aluminium, silicon and phosphorus are all Period 3 elements in the Periodic Table. Three statements concerning the oxides and chlorides of these elements are given. Which statements are correct?

Chemical bonding

Which species counts as a free radical?

Chemical bonding

The table sets out a comparison between calcium and barium, as well as calcium carbonate and barium carbonate. Which row is the correct one?

Group 2

P and Q are two solutions at equal concentration, each holding a different Group 2 ion. One has $\text{Mg}^{2+}$, while the other has $\text{Ba}^{2+}$. Separate $5\,\text{cm}^3$ portions of P and Q are tested. test 1: introduce $1\,\text{cm}^3$ of $0.1\,\text{mol dm}^{-3}$ $\text{Na}_2\text{SO}_4(aq)$ test 2: introduce $1\,\text{cm}^3$ of $0.1\,\text{mol dm}^{-3}$ $\text{NaOH}(aq)$ What observations are obtained in these tests?

Equilibria

J dissolves in water, forming aqueous solution K. When aqueous silver nitrate is added to K, a dense white precipitate is produced. On heating K with aqueous potassium hydroxide, a gas is released that turns moist universal indicator paper blue. Identify J.

Nitrogen compounds

Ammonium sulfate, $(\text{NH}_4)_2\text{SO}_4$, and ammonium nitrate, $\text{NH}_4\text{NO}_3$, are employed as fertilisers. These salts contain different percentages by mass of nitrogen. They produce the same effect as one another on the pH of moist neutral soil. Which row is right?

Atoms, molecules and stoichiometry

This equation represents a reaction taking place in a catalytic converter between carbon monoxide and nitrogen monoxide. $\text{2CO(g)} + \text{2NO(g)} \rightarrow \text{2CO}_2\text{(g)} + \text{N}_2\text{(g)}$ Which statement is correct?

Electrochemistry

Which compound is represented by the molecular formula $\text{C}_6\text{H}_{10}\text{O}$?

Atoms, molecules and stoichiometry

The general formula for a non-cyclic alcohol is $\text{C}_n\text{H}_{2n+1}\text{OH}$. For $n = 3$ and for $n = 4$, how many distinct structural isomers exist?

Hydroxy compounds

Compound X, $\text{C}_5\text{H}_{10}\text{O}_3$, contains one chiral carbon atom in each molecule. It gives bubbles with Na but shows no reaction with $\text{Na}_2\text{CO}_3$. Which formula could be used to represent compound X?

Hydroxy compounds

When ethane reacts with an excess of chlorine in ultraviolet light, a mixture of products is produced. How many of these products have two carbon atoms and one or more chlorine atoms?

Halogen compounds

When bromoethane is reacted with hot ethanolic sodium hydroxide, a colourless gas is produced. This gas causes aqueous bromine to lose its colour. What is the colourless gas?

Hydrocarbons

Which of the following statements is correct?

The Periodic Table: chemical periodicity

Alkynes are hydrocarbons containing a single triple $\text{C} \equiv \text{C}$ bond. As with alkenes, alkynes undergo addition reactions, and this can produce a saturated compound. For instance, ethyne, $\text{H}-\text{C} \equiv \text{C}-\text{H}$, reacts with excess hydrogen to give ethane. Propyne, $\text{C}_3\text{H}_4$, reacts with excess hydrogen bromide by addition in two steps. Markovnikov’s rule is used for the addition of HBr in each step. Which is the main product formed when propyne reacts with excess hydrogen bromide?

Hydrocarbons

During electrophilic addition of bromine to alkenes, a cation appears as the intermediate species. Which combination would lead to the most stable intermediate cation?

Hydrocarbons

Halogenoalkanes undergo reaction with hot ethanolic potassium cyanide. The mechanism for this reaction is either $\text{S}_\text{N}1$ or $\text{S}_\text{N}2$. Which statement is true?

Halogen compounds

X, Y and Z are three alcohol isomers. X: $\text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\text{CH}_2\text{OH}$ Y: $\text{CH}_3\text{CH}_2\text{CH(OH)CH}_2\text{CH}_3$ Z: $(\text{CH}_3)_2\text{C(OH)CH}_2\text{CH}_3$ Individual samples of each alcohol are heated with a mild oxidising agent and the observations are recorded. When dehydrated, one of these alcohols will form a pair of cis-trans isomers with molecular formula $\text{C}_5\text{H}_{10}$. Which row is correct?

Hydroxy compounds

Compound G forms a pale yellow precipitate with alkaline $\text{I}_2\text{(aq)}$. Which compound could G be?

Carbonyl compounds

The reaction pathway between ethanal and hydrogen cyanide begins with the step illustrated below. Which is the correct structure of the intermediate ion produced, and what happens next in this mechanism?

Carbonyl compounds

Which compound gives a reaction with 2,4-dinitrophenylhydrazine reagent but shows no reaction with Tollens’ reagent?

Carbonyl compounds

Compound X exhibits stereoisomerism and produces a precipitate when it is warmed with Fehling’s reagent. What might the structure of compound X be?

Chemical bonding

Which reaction would produce propanoic acid?

Carboxylic acids and derivatives

Lactide is used as an intermediate in the production of a synthetic fibre. Which compound is able to form lactide when it is heated in the presence of an acid catalyst?

Carboxylic acids and derivatives

When $1$ mole of hexane burns in excess oxygen, how many moles of products are produced?

Atoms, molecules and stoichiometry

The diagram gives the relative amounts of the various isotopes of lead present in a sample of lead ore. The abundance of 208 is half the abundance of 206. The abundances of 208 and 209 are the same. What is the relative atomic mass of the lead in the sample?

Atomic structure

Distinct samples, each with a mass of $1.0\,\text{g}$, of the compounds in the list are each reacted with an excess of dilute acid. Which compound gives off the greatest amount of $\text{CO}_2$?

Atoms, molecules and stoichiometry

Which of the statements concerning the $\text{Cl-N=O}$ molecule is correct?

Chemical bonding

Which row shown is the correct one?

The Periodic Table: chemical periodicity

A vessel has a volume of $1.20 \times 10^{-3}\,\text{m}^3$. Inside it is pure argon at a pressure of $1.00 \times 10^5\,\text{Pa}$ and a temperature of $25.0\,^{\circ}\text{C}$. For these conditions, argon may be assumed to behave as an ideal gas. What mass of argon is present?

States of matter

A student combined $25.0\,\text{cm}^3$ of $4.00\,\text{mol dm}^{-3}$ hydrochloric acid with the same volume of $4.00\,\text{mol dm}^{-3}$ sodium hydroxide. At the start, each solution was at $15.0\,^{\circ}\text{C}$. The highest temperature reached was $30.0\,^{\circ}\text{C}$. Assume the heat capacity of the final solution is $4.18\,\text{J K}^{-1}\text{ g}^{-1}$ and that its density is $1.00\,\text{g cm}^{-3}$. Calculate the enthalpy change of neutralisation of hydrochloric acid.

Chemical energetics

Propanoic acid is reacted with reagent X at room temperature. The reaction gives sodium propanoate as the organic product. No gas is given off in this reaction. What could reagent X be?

Carboxylic acids and derivatives

Which equation shows the reaction for which the standard enthalpy change is the standard enthalpy change of formation of water?

Chemical energetics

Which combination will react to produce exactly one mole of water?

Atoms, molecules and stoichiometry

The enthalpy change of neutralisation for $\text{HNO}_3(aq)$ reacting with $\text{NaOH}(aq)$ is $-57.0\ \text{kJ mol}^{-1}$. During an experiment, $20.0\ \text{cm}^3$ of $4.00\ \text{mol dm}^{-3}\ \text{HNO}_3$ is combined with $30.0\ \text{cm}^3$ of $2.00\ \text{mol dm}^{-3}\ \text{NaOH}$ in an insulated container. Both solutions begin at $25.0\ ^\circ\text{C}$. You may assume that the heat capacity of the product mixture is $4.2\ \text{J cm}^{-3}\ ^\circ\text{C}^{-1}$ and that no heat is lost. What is the highest final temperature reached by the mixture?

Chemical energetics

A table of some bond energies is shown. One mole of hydrogen reacts with oxygen to form water vapour. By using the bond energy data, what is the enthalpy change for this reaction?

Chemical energetics

Which particle has nitrogen in the same oxidation state as in the ion $\text{N}_2\text{O}_2^{2-}$?

Nitrogen compounds

Sulfur dioxide reacts with oxygen as shown. $\text{2SO}_2(g) + \text{O}_2(g) \rightleftharpoons \text{2SO}_3(g)$, $\Delta H^\circ = -197\ \text{kJ mol}^{-1}$. Which alteration will shift the equilibrium position to the right and alter the value of the equilibrium constant, $K_c$?

Equilibria

Solutions X and Y each have a concentration of $0.10\ \text{mol dm}^{-3}$. A measured volume of solution X is placed in a conical flask, then solution Y is delivered from a burette into the flask. The mixture is titrated. The diagram illustrates the pH titration curve for the acid-base reaction between the two solutions. What are solutions X and Y?

Equilibria

Which row gives the predicted properties of astatine when it is compared with iodine?

Group 17

The rate of an exothermic reaction is tracked by recording the concentration of a reactant at fixed time intervals. Throughout the experiment, the temperature of the reaction mixture is not controlled. Which graph shows how the concentration of the reactant changes with time?

Reaction kinetics

For one reversible reaction, the backward reaction is endothermic. The activation energy of the backward reaction is $160\ \text{kJ mol}^{-1}$. It may be assumed that the backward reaction follows a mechanism that is exactly the reverse of the mechanism for the forward reaction. Which statement about the activation energy of the forward reaction is correct?

Chemical energetics

This ionic equation represents iodide ions reacting with manganate(VII) ions in acidic solution. $u\text{MnO}_4^- + v\text{H}^+ + w\text{I}^- \rightarrow x\text{Mn}^{2+} + y\text{H}_2\text{O} + z\text{I}_2$ The letters $u$, $v$, $w$, $x$, $y$ and $z$ each stand for whole numbers. At least two of $u$, $v$, $w$, $x$, $y$ and $z$ are equal to one another. What is the least possible value of $v$?

Electrochemistry

$\text{HCN}$ has been found in interstellar gas. The molecules below have also been found in interstellar gas. Which molecule has the same overall number of valence shell (outer shell) electrons as $\text{HCN}$?

Chemical bonding

The diagram illustrates the Boltzmann distribution for the energy of gaseous molecules at one specific temperature. Which statement is correct?

Reaction kinetics

Magnesium and phosphorus are each reacted on their own with an excess of oxygen to produce their oxides. Each oxide is then added separately to water, and the pH values of the solutions formed are measured. The same two elements are each reacted on their own with an excess of chlorine to produce their chlorides. Each chloride is then added separately to water, and the pH values of the solutions formed are measured. Which row is correct?

The Periodic Table: chemical periodicity

The same volumes of saturated solutions of magnesium hydroxide, calcium hydroxide and strontium hydroxide are fully neutralised by dilute sulfuric acid. The water is then carefully evaporated from each solution formed, so that the matching solid sulfates are left behind. These solid sulfates are next dissolved completely in the smallest amount of water needed to make saturated solutions. Which statement about the volumes of water required to dissolve the sulfates is correct?

Group 2

Which of the following statements about the halogens is correct?

Group 17

When concentrated sulfuric acid is added to solid sodium bromide, bromine gas is formed together with several other products. In contrast, when concentrated sulfuric acid is added to solid sodium chloride, the products are only hydrogen chloride and sodium hydrogensulfate. Why does this difference occur?

Electrochemistry

Which of the following statements about nitrogen oxides is correct?

Nitrogen and sulfur

When responding to this question, take both structural isomerism and stereoisomerism into account. 2-bromopentane is heated with excess ethanolic sodium hydroxide. How many different hydrocarbons are formed?

Chemical bonding

Which compound is a secondary alcohol capable of being dehydrated to produce an alkene with $M_r = 70$?

Hydroxy compounds

Changing propan-1-ol into propan-2-ol can be carried out by a two-step synthesis. In the first step, the propan-1-ol is heated with concentrated sulfuric acid. Which reagent is required to carry out the second stage?

Hydroxy compounds

A sample of rock has a mass of $2.00\,\text{g}$. It contains calcium carbonate, but no other basic substances. It completely neutralises $36.0\,\text{cm}^3$ of $0.500\,\text{mol dm}^{-3}$ hydrochloric acid. What is the percentage by mass of calcium carbonate in the $2.00\,\text{g}$ sample of rock?

Atoms, molecules and stoichiometry

What type of reaction takes place during the hydrolysis of 2-bromopropane?

Chemical bonding

A mixture of ethane and an excess of chlorine is exposed to UV light. How many different products, each with only two carbon atoms and at least one chlorine atom in each molecule, could be formed?

Halogen compounds

On reaction of 1-methylcyclohexene with $\text{Br}_2$, the product formed is $X$. On reaction of 1-methylcyclohexene with HBr, the major product formed is $Y$. Which statement is correct?

Hydrocarbons

T is an organic compound that has $66.7\%$ by mass of carbon. Each molecule of T also contains one oxygen atom. T gives a yellow precipitate when it reacts with alkaline $\text{I}_2\text{(aq)}$. Identify T.

Atoms, molecules and stoichiometry

Which statement concerning butanone is correct?

Carbonyl compounds

At room temperature, HBr adds to methylbut-2-ene, giving compound X as the main product. When compound X is treated with KCN in ethanol, compound Y is formed. Acid hydrolysis of compound Y produces compound Z. Which compound is Z?

Organic synthesis

Compound Q may be hydrolysed by $\text{HCl(aq)}$. The two products formed in this hydrolysis have the same empirical formula. What might Q be?

Carboxylic acids and derivatives

An unsaturated carboxylic acid reacts with alcohol X to produce an ester. The ester structure is displayed. Which geometrical isomer is represented in this ester, and to which class of alcohol does X belong?

Carboxylic acids and derivatives

Which two-stage process changes cyclohexanol into cyclohexane-1,2-diol?

Hydroxy compounds

In polymer G, each carbon atom in the polymer chain is attached to one hydrogen atom and one methyl group. Which alkene could be polymerised to produce polymer G?

Polymerisation

L and M are elements from Period 3 of the Periodic Table. Neither one is argon. Details of the Pauling electronegativity values for L and M are given below: - L: the greatest of the seven elements Na to Cl - M: the smallest of the seven elements Na to Cl There are three statements about elements L and M. Which statements are correct?

Chemical bonding

The mass spectrum for compound X shows M, M+1 and M+2 peaks, and there are other peaks as well. Peak M is the molecular ion peak, $\text{M}^+$. The relative abundance of peak M is fifteen times that of peak M+1. Peaks M and M+2 have the same height. Which compound could X be?

Analytical techniques

Ammonia reacts with acids to produce the ammonium ion. $\text{NH}_3 + \text{H}^+ \rightleftharpoons \text{NH}_4^+$ Which row is the correct one?

Equilibria

Variations in electronegativity can be used to help determine the oxidation number of an atom in different species. The rules that are applied include: - The atom with the higher electronegativity is given a negative oxidation number. - Hydrogen is more electronegative than Group 1 metals. - Oxygen is more electronegative than hydrogen. Which row is correct?

Electrochemistry

What assumptions are made for ideal gases?

States of matter

A sample of water with volume $200\,\text{cm}^3$ contains dissolved oxygen gas. When this oxygen gas is measured, its volume is $6.00\,\text{cm}^3$ at $1.00 \times 10^5\,\text{Pa}$ and $35^\circ\text{C}$. Calculate the concentration of oxygen gas in the water. (Assume that oxygen behaves as an ideal gas.)

Atoms, molecules and stoichiometry

Which statement explains the lower melting point of buckminsterfullerene compared with graphite?

Chemical bonding