A Level Chemistry 9701 Paper 11, Oct/Nov 2023

Sodium azide, ${\mathrm{N}\mathrm{a}\mathrm{N}}_3$ is an explosive used to inflate airbags in cars when they crash. It consists of positive sodium ions and negative azide ions. What are the numbers of electrons in the sodium ion and the azide ion?

The graph shows the variation of the first ionisation energy with proton number for some elements. The letters used are not the actual symbols for the elements. Which statement about the elements is correct? A P and X are in the same period in the Periodic Table. B The general increase from Q to X is due to increasing atomic radius. C The small decrease from R to S is due to decreased shielding. D The small decrease from U to V is due to repulsion between paired electrons.

Aluminium carbide, ${\mathrm{A}\mathrm{l}}_4{\mathrm{C}}_3$, reacts readily with aqueous sodium hydroxide. The two products of the reaction are ${\mathrm{N}\mathrm{a}\mathrm{A}\mathrm{l}\mathrm{O}}_2$ and a hydrocarbon. Water molecules are also involved as reactants. What is the formula of the hydrocarbon? A ${\mathrm{C}\mathrm{H}}_4$ B ${\mathrm{C}}_2{\mathrm{H}}_6$ C ${\mathrm{C}}_3{\mathrm{H}}_8$ D ${\mathrm{C}}_6{\mathrm{H}}_{12}$

A sample of $35.6\text{ g}$ of hydrated sodium carbonate contains $25.84\mathrm{\%}$ sodium ions by mass. When this sample is heated, anhydrous sodium carbonate and water are formed. Which mass of water is given off? A $7.2\text{ g}$ B $10.6\text{ g}$ C $14.4\text{ g}$ D $21.2\text{ g}$

Solid aluminium chloride sublimes at ${178}^{\circ }\mathrm{C}$. Which structure best represents the species in the vapour at this temperature?

Which row is correct?

When an evacuated tube of volume $400{\text{ cm}}^3$ is filled with gas at $300\text{ K}$ and $101\text{ kPa}$, the mass of the tube increases by $0.65\text{ g}$. Assume the gas behaves as an ideal gas. What is the identity of the gas? A argon B helium C krypton D neon

Nitrogen, ${\mathrm{N}}_2$, and carbon monoxide, $\mathrm{C}\mathrm{O}$, both have $M_r=28$. The boiling point of ${\mathrm{N}}_2$ is $77\text{ K}$. The boiling point of $\mathrm{C}\mathrm{O}$ is $82\text{ K}$. What could be responsible for this difference in boiling points? A $\mathrm{C}\mathrm{O}$ molecules have a permanent dipole; the ${\mathrm{N}}_2$ molecules are not polar. B ${\mathrm{N}}_2$ has $\sigma$ and $\pi$ bonding; $\mathrm{C}\mathrm{O}$ has $\sigma$ bonding only. C ${\mathrm{N}}_2$ has a strong $\mathrm{N}\equiv \mathrm{N}$ bond; $\mathrm{C}\mathrm{O}$ has a $\mathrm{C}=\mathrm{O}$ bond. D The $\mathrm{C}\mathrm{O}$ molecule has more electrons than the ${\mathrm{N}}_2$ molecule.

Which statement about enthalpy changes is correct? A Enthalpy changes of reaction are always negative. B Enthalpy changes of combustion are always positive. C Enthalpy changes of formation are always positive. D Enthalpy changes of neutralisation are always negative.

What is the definition of standard enthalpy change of neutralisation, $\mathrm{\Delta }{H}_{\text{neut}}^{\ominus }$? A $\mathrm{\Delta }{H}_r^{\ominus }$ when one mole of an aqueous acid is neutralised by an aqueous alkali B $\mathrm{\Delta }{H}_r^{\ominus }$ when one mole of an aqueous alkali is neutralised by an aqueous acid C $\mathrm{\Delta }{H}_r^{\ominus }$ when one mole of an aqueous acid is neutralised by one mole of an aqueous alkali D $\mathrm{\Delta }{H}_r^{\ominus }$ when an aqueous acid and an aqueous alkali react together to produce one mole of water

$\mathrm{H}\mathrm{O}\mathrm{C}\mathrm{l}(\mathrm{a}\mathrm{q})$ is the molecule that kills bacteria when chlorine is added to water. The following reaction produces this molecule. $${\mathrm{C}\mathrm{l}}_2(\mathrm{g})+{\mathrm{H}}_2\mathrm{O}(\mathrm{l})\rightleftharpoons \mathrm{H}\mathrm{O}\mathrm{C}\mathrm{l}(\mathrm{a}\mathrm{q})+{\mathrm{H}}^{+}(\mathrm{a}\mathrm{q})+{\mathrm{C}\mathrm{l}}^{-}(\mathrm{a}\mathrm{q})$$ Which statement about this reaction is correct? A Chlorine is both oxidised and reduced. B Chlorine is oxidised but not reduced. C Hydrogen is both oxidised and reduced. D Hydrogen is oxidised but not reduced.

Nitrogen dioxide, ${\mathrm{N}\mathrm{O}}_2$, exists in equilibrium with dinitrogen tetroxide, ${\mathrm{N}}_2{\mathrm{O}}_4$. $$2{\mathrm{N}\mathrm{O}}_2(\mathrm{g})\rightleftharpoons {\mathrm{N}}_2{\mathrm{O}}_4(\mathrm{g})\mathrm{\Delta }H=-57{\text{ kJ mol}}^{-1}$$ Which conditions give the greatest percentage of ${\mathrm{N}}_2{\mathrm{O}}_4(\mathrm{g})$ at equilibrium?

When an equimolar mixture of ${\mathrm{H}}_2$ and ${\mathrm{I}}_2$ react, the mole fraction of $\mathrm{H}\mathrm{I}$ in the final mixture is $x$. What is the equilibrium constant, $K_p$, for the reaction? A ${\displaystyle \frac{x^2}{(1-x{)}^2}}$ B ${\displaystyle \frac{x^2}{(1-2x{)}^2}}$ C ${\displaystyle \frac{4x^2}{(1-x{)}^2}}$ D ${\displaystyle \frac{4x^2}{(1-2x{)}^2}}$

In reaction 1, a student measures the initial rate of production of ${\mathrm{C}\mathrm{O}}_2(\mathrm{g})$ when ${\mathrm{C}\mathrm{u}\mathrm{C}\mathrm{O}}_3(\mathrm{s})$ is added to $50{\text{ cm}}^3$ of $0.1{\text{ mol dm}}^{-3}{\mathrm{H}\mathrm{N}\mathrm{O}}_3(\mathrm{a}\mathrm{q})$. In reaction 2, the student repeats the experiment using $50{\text{ cm}}^3$ of $0.5{\text{ mol dm}}^{-3}{\mathrm{H}\mathrm{N}\mathrm{O}}_3(\mathrm{a}\mathrm{q})$ and the same mass of ${\mathrm{C}\mathrm{u}\mathrm{C}\mathrm{O}}_3(\mathrm{s})$. In reaction 1 and reaction 2, the acid is in excess and samples of the same ${\mathrm{C}\mathrm{u}\mathrm{C}\mathrm{O}}_3$ powder are used. Which row is correct?

The forward reaction of a reversible reaction is exothermic and has an activation energy of $+30{\text{ kJ mol}}^{-1}$. The reverse reaction proceeds by a mechanism that is the exact reverse of the mechanism of the forward reaction. Which statement about the activation energy of the reverse reaction is correct? A The activation energy for the reverse reaction is equal to $-30{\text{ kJ mol}}^{-1}$. B The activation energy for the reverse reaction is greater than $0{\text{ kJ mol}}^{-1}$ but less than $+30{\text{ kJ mol}}^{-1}$. C The activation energy for the reverse reaction is equal to $+30{\text{ kJ mol}}^{-1}$. D The activation energy for the reverse reaction is greater than $+30{\text{ kJ mol}}^{-1}$.

X, Y and Z are elements all found within Groups 13, 14 and 15 of the Periodic Table. X is in the same group in the Periodic Table as Y. Y and Z are in Period 3. The first ionisation energy of X is greater than the first ionisation energy of Y. The melting point of Z is less than the melting point of Y. Y and Z both form chlorides which are white solids. These white solids react with water to produce solutions with a pH of less than 4. Which row of the table shows the possible identities of X and Y?

Which row about silicon, Si, and magnesium, Mg, and their ions is correct?

Bromocresol green is an acid-base indicator. Below a pH of 3.8 it is yellow. Above a pH of 5.4 it is blue. Between these values it is green. Bromocresol green is added to the aqueous solution formed when the chloride of element T is added to water. The colour becomes yellow. When an excess of the solid oxide of element U is slowly added to this yellow solution, the indicator turns green then blue. Which row could identify element T and element U?

Which row correctly describes the separate reactions of calcium and strontium with water?

L and M are both compounds of Group 2 elements. L and M are both soluble in water. When solutions of L and M are mixed, a white precipitate is formed. What could be L and M? A barium chloride and magnesium sulfate B barium sulfate and magnesium chloride C barium nitrate and magnesium chloride D barium carbonate and magnesium nitrate

A $5.00\text{ g}$ sample of an anhydrous Group 2 metal nitrate loses $3.29\text{ g}$ in mass when heated strongly. Which metal is present? A magnesium B calcium C strontium D barium

In this question, Q represents an atom of chlorine, bromine or iodine. Which explanation for the variation in volatility down Group 17 is correct? A Instantaneous dipole–induced dipole forces between molecules become stronger. B Permanent dipole–permanent dipole forces between molecules become stronger. C The bond energy of the ${\mathrm{Q}}_2$ molecules decreases. D The first ionisation energy $\mathrm{Q}(\mathrm{g})\to {\mathrm{Q}}^{+}(\mathrm{g})+{\mathrm{e}}^{-}$ decreases.

Which statement about the halogens or halide ions is correct? A Bromide ions react to form a white precipitate when added to silver nitrate solution. B Bromine does not oxidise chloride ions when added to sodium chloride solution. C Fluorine atoms form cations by accepting electrons when they react. D Chloride ions are stronger reducing agents than iodide ions.

If ammonium cyanate is heated in the absence of air, the only product of the reaction is urea, $\mathrm{C}\mathrm{O}({\mathrm{N}\mathrm{H}}_2{)}_2$. No other products are formed in the reaction. What is the formula of the cyanate ion present in ammonium cyanate? A ${\mathrm{C}\mathrm{O}\mathrm{N}}_2^{-}$ B ${\mathrm{C}\mathrm{O}\mathrm{N}}_2^{2-}$ C ${\mathrm{O}\mathrm{C}\mathrm{N}}^{-}$ D ${\mathrm{O}\mathrm{C}\mathrm{N}}^{2-}$

Hexamine is a crystalline solid used as a fuel in portable stoves. The diagram shows its skeletal structure. What is the empirical formula of hexamine? A ${\mathrm{C}\mathrm{H}}_2\mathrm{N}$ B ${\mathrm{C}}_3{\mathrm{H}}_6{\mathrm{N}}_2$ C ${\mathrm{C}}_4{\mathrm{H}}_8{\mathrm{N}}_4$ D ${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{N}}_4$

The compound aspartame is widely used as a sweetener in ‘diet’ soft drinks. Aspartame is chiral. (There are no chiral carbon atoms in ${\mathrm{C}}_6{\mathrm{H}}_5$.) How many chiral carbon atoms are present in a molecule of aspartame? A 1 B 2 C 3 D 4

How many $\sigma$ and $\pi$ bonds are in the molecule ${\mathrm{H}\mathrm{C}\mathrm{C}\mathrm{C}\mathrm{H}}_2{\mathrm{C}\mathrm{H}}_2\mathrm{C}\mathrm{H}\mathrm{C}({\mathrm{C}\mathrm{H}}_3{)}_2$?

The hydrocarbon ${\mathrm{C}}_{17}{\mathrm{H}}_{36}$ can be cracked. Which compound is the least likely to be produced in this reaction? A ${\mathrm{C}}_3{\mathrm{H}}_8$ B ${\mathrm{C}}_4{\mathrm{H}}_8$ C ${\mathrm{C}}_8{\mathrm{H}}_{16}$ D ${\mathrm{C}}_{16}{\mathrm{H}}_{34}$

Which compound has an $M_r$ of 84 and will react with $\mathrm{H}\mathrm{B}\mathrm{r}$ to give a product with an $M_r$ of 164.9?

$\beta$-carotene is responsible for the orange colour of carrots. $\beta$-carotene is oxidised by hot, concentrated, acidified ${\mathrm{K}\mathrm{M}\mathrm{n}\mathrm{O}}_4$. When an individual molecule of $\beta$-carotene is oxidised in this way, many product molecules are formed. How many of these product molecules contain a ketone functional group? A 4 B 6 C 9 D 11

1,1-dichloropropane reacts with aqueous sodium hydroxide in a series of steps to give propanal. $${\mathrm{C}\mathrm{H}}_3{\mathrm{C}\mathrm{H}}_2{\mathrm{C}\mathrm{H}\mathrm{C}\mathrm{l}}_2\stackrel{\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}(\mathrm{a}\mathrm{q})}{\to }{\mathrm{C}\mathrm{H}}_3{\mathrm{C}\mathrm{H}}_2\mathrm{C}\mathrm{H}\mathrm{O}$$ Which term describes the first step of this reaction? A addition B elimination C oxidation D substitution

Propanoic acid can be made from bromoethane using a two-stage synthesis. Which pair of reagents is most suitable?

Alcohol X gives a yellow precipitate with alkaline ${\mathrm{I}}_2(\mathrm{a}\mathrm{q})$. What is the structure of X?

When ethanol reacts with sodium metal, ethoxide ions, ${\mathrm{C}\mathrm{H}}_3{\mathrm{C}\mathrm{H}}_2{\mathrm{O}}^{-}$, are produced. When water reacts with sodium metal, ${\mathrm{O}\mathrm{H}}^{-}$ ions are produced. Which statement about these reactions and the ethoxide ion is correct? A At the same temperature, the rate of reaction between sodium and ethanol is greater than that between sodium and water. B ${\mathrm{C}\mathrm{H}}_3{\mathrm{C}\mathrm{H}}_2{\mathrm{O}}^{-}$ is a stronger base than ${\mathrm{O}\mathrm{H}}^{-}$ due to the electron-donating effect of the ethyl group. C The negative charge on the oxygen in an ethoxide ion is delocalised. D It is easier to deprotonate ethanol as it is more acidic than water.

Menthol is a naturally occurring alcohol. When menthol is heated with concentrated sulfuric acid it reacts. The products formed include compound T. What is the structure of compound T?

Which compound will produce a yellow-orange precipitate when added to 2,4-dinitrophenylhydrazine?

Ethanal, ${\mathrm{C}\mathrm{H}}_3\mathrm{C}\mathrm{H}\mathrm{O}$, undergoes an addition reaction with $\mathrm{H}\mathrm{C}\mathrm{N}$ in the presence of ${\mathrm{C}\mathrm{N}}^{-}$ ions. Which row identifies the type of reaction and the name of the product formed?

The structure of compound X is shown. What is produced when X is heated with $\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}(\mathrm{a}\mathrm{q})$?

The infrared spectrum of compound L is shown.

What is the structure of L? A ${\mathrm{H}\mathrm{O}\mathrm{C}\mathrm{H}}_2{\mathrm{C}\mathrm{O}\mathrm{C}\mathrm{H}}_2\mathrm{O}\mathrm{H}$ B ${\mathrm{H}\mathrm{O}\mathrm{C}\mathrm{H}}_2\mathrm{C}\mathrm{H}(\mathrm{O}\mathrm{H})\mathrm{C}\mathrm{H}\mathrm{O}$ C ${\mathrm{H}\mathrm{O}\mathrm{C}\mathrm{H}}_2\mathrm{C}\mathrm{H}(\mathrm{O}\mathrm{H}){\mathrm{C}\mathrm{H}}_2\mathrm{O}\mathrm{H}$ D ${\mathrm{H}\mathrm{O}\mathrm{C}\mathrm{H}}_2{\mathrm{C}\mathrm{H}}_2\mathrm{C}\mathrm{O}\mathrm{O}\mathrm{H}$

In the mass spectrum of compound J, the ratio of the height of the $\mathrm{M}+1$ ion peak to the height of the ${\mathrm{M}}^{+}$ ion peak is $4:91$. Compound J forms a carboxylic acid when heated with acidified ${\mathrm{K}}_2{\mathrm{C}\mathrm{r}}_2{\mathrm{O}}_7$. What is compound J? A butanal B butanone C propan-1-ol D propanenitrile