A Level Chemistry 9701 Paper 13, May/June 2025

Which isolated gaseous atom has a total of five electrons occupying spherically shaped orbitals? A sodium B fluorine C boron D potassium

Diagram 1 shows the reaction pathway for a reaction. Diagram 2 shows a graph of concentration of reactant against time for the same reaction. Which diagrams, drawn to the same scale, show the effect of increased temperature on this reaction?

The equation shows the overall reaction between an amine and an acid chloride. $$2{\text{CH}}_3{\text{CH}}_2{\text{NH}}_2+{\text{CH}}_3{\text{CH}}_2\text{COCl}\to {\text{CH}}_3{\text{CH}}_2{\text{CONHCH}}_2{\text{CH}}_3+{\text{CH}}_3{\text{CH}}_2{\text{NH}}_3\text{Cl}$$ The four steps in the mechanism are as follows. 1 ${\text{CH}}_3{\text{CH}}_2\text{C}(\text{O})\text{Cl}+{\text{H}}_2{\text{NCH}}_2{\text{CH}}_3\to {\text{CH}}_3{\text{CH}}_2\text{C}({\text{O}}^{-})(\text{Cl}){\text{N}}^{+}{\text{H}}_2{\text{CH}}_2{\text{CH}}_3$ 2 ${\text{CH}}_3{\text{CH}}_2\text{C}({\text{O}}^{-})(\text{Cl}){\text{N}}^{+}{\text{H}}_2{\text{CH}}_2{\text{CH}}_3\to {\text{CH}}_3{\text{CH}}_2\text{C}(=\text{O}){\text{N}}^{+}{\text{H}}_2{\text{CH}}_2{\text{CH}}_3+{\text{Cl}}^{-}$ 3 ${\text{CH}}_3{\text{CH}}_2\text{C}(=\text{O}){\text{N}}^{+}{\text{H}}_2{\text{CH}}_2{\text{CH}}_3+{\text{Cl}}^{-}\to {\text{CH}}_3{\text{CH}}_2\text{C}(=\text{O}){\text{NHCH}}_2{\text{CH}}_3+\text{HCl}$ 4 ${\text{CH}}_3{\text{CH}}_2{\text{NH}}_2+\text{HCl}\to {\text{CH}}_3{\text{CH}}_2{\text{NH}}_3\text{Cl}$ Which steps are Brønsted–Lowry acid–base reactions? A 1 and 3 B 3 and 4 C 3 only D 4 only

Chromium is present in compound X. ● Two moles of compound X react with exactly 3 moles of silicon. ● The only products of this reaction are 4 moles of chromium and 3 moles of a silicon compound in which the oxidation state of the silicon is +4. ● Chromium and silicon are the only elements that change their oxidation states in this reaction. What could be the identity of compound X? A ${\text{Cr}}_2{\text{O}}_3$ B ${\text{Cr}}_2{\text{H}}_6$ C ${\text{Cr}}_2{\text{H}}_4$ D ${\text{Cr}}_2{\text{O}}_4$

The reversible reaction shown is in equilibrium at a temperature of $450{}^{\circ }\text{C}$. $${\text{H}}_2+{\text{I}}_2\rightleftharpoons 2\text{HI}\mathrm{\Delta }H=-9.5\text{kJ}{\text{mol}}^{-1}$$ The table shows the equilibrium concentrations in the reaction mixture.

The temperature of the reaction mixture is increased at constant volume. The concentration of one of the components falls to $0.80\text{mol}{\text{dm}}^{-3}$ at equilibrium under these conditions. What is the concentration of ${\text{H}}_2$ in the new equilibrium mixture? A $0.80\text{mol}{\text{dm}}^{-3}$ B $0.93\text{mol}{\text{dm}}^{-3}$ C $1.11\text{mol}{\text{dm}}^{-3}$ D $1.20\text{mol}{\text{dm}}^{-3}$

The first stage in the industrial production of nitric acid from ammonia can be represented by the following equation. $$4{\text{NH}}_3(\text{g})+5{\text{O}}_2(\text{g})\rightleftharpoons 4\text{NO}(\text{g})+6{\text{H}}_2\text{O}(\text{g})$$ Using the following standard enthalpy change of formation data, what is the value of the standard enthalpy change, $\mathrm{\Delta }{H}^{\circ }$, for this reaction?

A $+905.2\text{kJ}{\text{mol}}^{-1}$ B $-105.4\text{kJ}{\text{mol}}^{-1}$ C $-905.2\text{kJ}{\text{mol}}^{-1}$ D $-1274.0\text{kJ}{\text{mol}}^{-1}$

The gaseous compound Z decomposes on heating. In the diagram, Boltzmann distributions for Z at two different temperatures, P and Q, are shown. The lines X and Y indicate activation energies for the decomposition of Z with and without a catalyst. Which curve and which line describe the decomposition of Z at a higher temperature and with a catalyst present?

The structure of a molecule found in food is shown. Four statements about the molecule are listed. 1 This molecule contains only $\sigma$ bonds. 2 This molecule contains both $\sigma$ and $\pi$ bonds. 3 The six-membered ring is planar. 4 The six-membered ring is non-planar. Which two statements are correct? A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

In which substance are covalent bonds broken as it melts? A silicon(IV) oxide B ice C iodine D ethanol

Why is the second ionisation energy of sodium larger than the second ionisation energy of magnesium? A The attraction between the nucleus and the outer electron is greater in ${\text{Na}}^{+}$ than in ${\text{Mg}}^{+}$. B The nuclear charge of ${\text{Na}}^{+}$ is greater than that of ${\text{Mg}}^{+}$. C The outer electron of ${\text{Na}}^{+}$ is more shielded than the outer electron of ${\text{Mg}}^{+}$. D The outer electron of Na is in the same orbital as the outer electron of Mg.

${\text{BF}}_3$ reacts with ${\text{NH}}_3$ to form a single compound with a simple molecular structure. $${\text{BF}}_3+{\text{NH}}_3\to {\text{F}}_3{\text{B–NH}}_3$$ Which row describes how the bond angles change during the reaction?

The equation for the reaction of nitrogen with hydrogen is shown. $${\text{N}}_2(\text{g})+3{\text{H}}_2(\text{g})\rightleftharpoons 2{\text{NH}}_3(\text{g})\mathrm{\Delta }{H}_{\text{r}}^{\circ }=-92.2\text{kJ}{\text{mol}}^{-1}$$ Which statement is correct? A $\mathrm{\Delta }{H}_{\text{r}}^{\circ }$ is measured at $298{}^{\circ }\text{C}$. B $\mathrm{\Delta }{H}_{\text{r}}^{\circ }$ is measured at $101\text{kPa}$. C $\mathrm{\Delta }{H}_{\text{r}}^{\circ }$ represents the standard enthalpy change for the formation of ammonia gas. D $\mathrm{\Delta }{H}_{\text{r}}^{\circ }$ represents the enthalpy change when $1.0\text{mol}$ of ${\text{N}}_2(\text{g})$ reacts with $1.0\text{mol}$ of ${\text{H}}_2(\text{g})$.

Hydrogen peroxide, ${\text{H}}_2{\text{O}}_2$, decomposes into water and oxygen when a suitable catalyst is added. $20.0{\text{cm}}^3$ of aqueous hydrogen peroxide decomposes to produce $600{\text{cm}}^3$ of oxygen at room conditions. What is the concentration of the aqueous hydrogen peroxide? A $5.00\text{mol}{\text{dm}}^{-3}$ B $2.50\text{mol}{\text{dm}}^{-3}$ C $1.25\text{mol}{\text{dm}}^{-3}$ D $0.625\text{mol}{\text{dm}}^{-3}$

When $0.15\text{g}$ of an organic compound is vaporised, it occupies a volume of $65.0{\text{cm}}^3$ at $405\text{K}$ and $1.00\times {10}^5\text{Pa}$. Using the expression $pV=nRT$, which expression should be used to calculate the relative molecular mass, $M_{\text{r}}$, of the compound? A $\frac{0.15\times 65\times {10}^{-6}\times 1\times {10}^5}{8.31\times 405}$ B $\frac{0.15\times 8.31\times 405}{1\times {10}^5\times 65\times {10}^{-3}}$ C $\frac{0.15\times 65\times {10}^{-3}\times 1\times {10}^5}{8.31\times 405}$ D $\frac{0.15\times 8.31\times 405}{1\times {10}^5\times 65\times {10}^{-6}}$

A washing powder contains sodium hydrogencarbonate, ${\text{NaHCO}}_3$, as one of the ingredients. In a titration, a solution containing $1.00\text{g}$ of this washing powder requires $7.15{\text{cm}}^3$ of $0.100\text{mol}{\text{dm}}^{-3}$ sulfuric acid for complete reaction. The sodium hydrogencarbonate is the only ingredient that reacts with the acid. What is the percentage by mass of sodium hydrogencarbonate in the washing powder? A $3.0\mathrm{\%}$ B $6.0\mathrm{\%}$ C $12.0\mathrm{\%}$ D $24.0\mathrm{\%}$

The flow chart shows some reactions of nitrogen compounds. $$\text{gas 1}\stackrel{\text{acid}}{\to }\text{salt 1}\stackrel{\text{alkali}}{\to }\text{salt 2 + other products}$$ Which row identifies gas 1 and salt 2?

Mixing aqueous silver nitrate and aqueous sodium chloride produces a precipitate. Addition of which reagent to the mixture gives a colourless solution? A aqueous ammonia B aqueous potassium iodide C dilute hydrochloric acid D dilute nitric acid

Which statement is correct? A Barium oxide reacts with water at room temperature to form barium hydroxide and hydrogen. B Calcium oxide does not react with water at room temperature. C Magnesium hydroxide reacts with steam to form magnesium oxide and hydrogen. D Strontium oxide reacts with water at room temperature to form strontium hydroxide only.

Which statement about the properties of halogens and hydrogen halides is correct? A A chloride ion is a stronger reducing agent than an iodide ion. B Chlorine is more volatile than bromine because chlorine has stronger intermolecular forces. C Hydrogen bromide is more thermally stable than hydrogen iodide because it has a stronger covalent bond. D Iodine is less reactive than bromine because iodine has weaker covalent bonds.

Three statements about the chemical periodicity of Period 3 oxides are listed. 1 The maximum oxidation state of the Period 3 elements in their oxides increases from sodium to phosphorus, then decreases from phosphorus to sulfur. 2 The oxides from sodium to aluminium dissolve in water without hydrolysis; from silicon to sulfur they are hydrolysed by water. 3 The structure and bonding changes from giant ionic to giant covalent to simple molecular. Which statements are correct? A 1, 2 and 3 B 1 only C 2 and 3 only D 3 only

Which dot-and-cross diagrams represent molecules that can react with unburned hydrocarbons to form peroxyacetyl nitrate, PAN, a component of photochemical smog? A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

Which set of three elements contains a single element that has both the highest melting point and the lowest electrical conductivity of the three elements in the set? A magnesium, aluminium and silicon B aluminium, silicon and phosphorus C sodium, magnesium and aluminium D silicon, phosphorus and chlorine

In which row do the particles increase in size?

W, X, Y and Z are Group 2 elements barium, calcium, magnesium and strontium but not in that order. W reacts faster with dilute hydrochloric acid than Y. The hydroxide of X is less soluble in water than the hydroxide of W. The sulfate of Y is the most soluble of the sulfates of W, X, Y and Z. The carbonate of Z decomposes more slowly than the carbonate of W at the same temperature. What is the $M_{\text{r}}$ of the nitrate of W? A 148.3 B 164.1 C 211.6 D 261.3

Polymer J has repeat unit –[CH(C2H5)CH(CH3)]–. Polymer K has repeat unit –[CH(CH3)CH(CH3)]–. Which row is correct?

$0.200\text{mol}$ ethanenitrile reacts with an excess of dilute sodium hydroxide. The reaction produces organic compound S and ammonia gas only. The reaction has an $80.0\mathrm{\%}$ yield. Which mass of S is produced? A $9.60\text{g}$ B $13.1\text{g}$ C $15.4\text{g}$ D $16.4\text{g}$

The structure of butenedioic acid is shown. When an excess of $\text{NaOH}(\text{aq})$ is added to butenedioic acid, which organic product is formed?

Four organic compounds are shown. A mixture of these four compounds reacts with hot aqueous sodium hydroxide. The products of this reaction are acidified. Which organic acids are present in the products? A butanoic, ethanoic and propanoic acids B butanoic, ethanoic and methanoic acids C ethanoic, 3-methylbutanoic and propanoic acids D methanoic, 3-methylbutanoic and propanoic acids

Ethanal reacts with KCN dissolved in liquid HCN. This reaction involves the formation of an intermediate. Which statement is correct? A HCN does not have any lone pairs of electrons and so ${\text{CN}}^{-}$ is the catalyst. B The ${\text{O}}^{\delta -}$ of C=O attacks ${\text{K}}^{+}$ in a nucleophilic attack. C A proton from HCN is transferred to the intermediate. D The reaction is a nucleophilic substitution.

What is formed when propanone is heated under reflux with a solution of ${\text{NaBH}}_4$? A propan-2-ol B propan-1-ol C propanal D propane

The compounds shown are all produced by plants. Each compound is warmed with acidified ${\text{K}}_2{\text{Cr}}_2{\text{O}}_7$. Which compound will give a different observation to the other three?

Structural and stereoisomerism should be considered when answering this question. How many alcohols with the molecular formula ${\text{C}}_5{\text{H}}_{12}\text{O}$ give a yellow precipitate with alkaline ${\text{I}}_2(\text{aq})$? A 2 B 3 C 4 D 5

An amine is produced in the following reaction. $${\text{C}}_2{\text{H}}_5\text{I}+2{\text{NH}}_3\to {\text{C}}_2{\text{H}}_5{\text{NH}}_2+{\text{NH}}_4\text{I}$$ What is the mechanism? A electrophilic addition B free-radical substitution C nucleophilic addition D nucleophilic substitution

The reaction shown can be used to lengthen a carbon chain. $${\text{CH}}_3{\text{CH}}_2{\text{CH}}_2\text{Br}+{\text{CN}}^{-}\to {\text{CH}}_3{\text{CH}}_2{\text{CH}}_2\text{CN}+{\text{Br}}^{-}$$ Which row shows the correct reagent and conditions for this reaction?

Which row shows the products formed when cyclohexene reacts with acidified ${\text{KMnO}}_4$ under different conditions?

Two steps in the free-radical substitution reaction between methane and chlorine are shown. step 1 ${\text{CH}}_3^{\bullet }+{\text{Cl}}_2\to {\text{CH}}_3\text{Cl}+{\text{Cl}}^{\bullet }$ step 2 ${\text{CH}}_3\text{Cl}+{\text{Cl}}^{\bullet }\to {\text{CH}}_2{\text{Cl}}^{\bullet }+\text{HCl}$ Which statement is correct? A Step 1 is initiation and step 2 is propagation. B Step 1 is propagation and step 2 is termination. C Step 1 is initiation and step 2 is termination. D Both steps are propagation.

Compound P displays cis/trans isomerism and gives a red-brown precipitate with Fehling’s solution. What is P?

Fructose is a sugar with more than one chiral centre. The fructose molecule is shown with X, Y and Z indicating three carbon atoms. Which carbon atoms are chiral centres? A X, Y and Z B X and Y only C X only D Y only

An organic compound, T, contains only one functional group. Compound T has the empirical formula ${\text{C}}_2{\text{H}}_4\text{O}$. Some functional groups are listed. 1 alcohol 2 aldehyde 3 ester 4 ketone Which functional groups are possible for compound T? A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

The mass spectrum of an organic compound has the following features. ● The molecular ion peak is at $m\mathrm{/}e=60$. This peak has a relative intensity = 100. ● There is a peak at $m\mathrm{/}e=61$, which has a relative intensity = 2.2. ● There is no fragment peak at $m\mathrm{/}e=17$. ● There is a fragment peak at $m\mathrm{/}e=31$. What could be the identity of the organic compound? A methyl methanoate, ${\text{HCOOCH}}_3$ B methoxyethane, ${\text{CH}}_3{\text{OC}}_2{\text{H}}_5$ C ethanoic acid, ${\text{CH}}_3\text{COOH}$ D propan-2-ol, ${\text{CH}}_3{\text{CH(OH)CH}}_3$