Chemistry SL Paper 1A, November 2025, TZ1

Which methods for separating the components of the given mixtures are correct? Mixture Method I. Two miscible liquids with boiling points of 56 °C and 118 °C Distillation II. The coloured pigments extracted from a leaf Paper chromatography III. A solid…

What is the number of subatomic particles in $\ce{^{88}Sr^2+}$? A. Protons: 40, neutrons: 50, electrons: 36 B. Protons: 38, neutrons: 50, electrons: 36 C. Protons: 38, neutrons: 88, electrons: 40 D. Protons: 40, neutrons: 88, electrons: 40

The diagrams show the 3s and 3p sublevels of a sulfur atom; the inner sublevels are full. Which diagram represents the ground-state electron configuration, in agreement with the Pauli exclusion principle and Hund's rule? A. Diagram A B. Diagram B C. Diagram C…

4.06 g of hydrated magnesium chloride, $\ce{MgCl2*6H2O}$ ($M_\mathrm{r}$ = 203), is dissolved in water to make 0.250 $\mathrm{dm^3}$ of solution. What is the concentration of chloride ions, in $\mathrm{mol\,dm^{-3}}$, in this solution? A. 0.0400 B. 0.0800 C.…

Under which conditions does the gas behave most like an ideal gas? A. Helium at 200 kPa and 300 K B. Helium at 20 kPa and 600 K C. Sulfur dioxide at 20 kPa and 600 K D. Sulfur dioxide at 200 kPa and 300 K

Part of the lattice of potassium bromide, KBr, is shown in an expanded view. Which statement about the lattice of potassium bromide is correct? A. Each bromide ion is in contact with six potassium ions. B. Neighbouring ions are held together by shared pairs of…

What are the electron domain geometry and the molecular geometry of sulfur dioxide, $\ce{SO2}$? A. Electron domain geometry: trigonal planar; molecular geometry: bent B. Electron domain geometry: trigonal planar; molecular geometry: trigonal planar C. Electron…

Which substance has dipole-dipole forces between its molecules? A. $\ce{CO2}$ B. $\ce{Cl2}$ C. $\ce{CH4}$ D. $\ce{CH3Cl}$

Which statement best explains why aluminium can be drawn into thin wires? A. The delocalized electrons carry charge through the metal. B. The layers of aluminium ions can slide over each other while the delocalized electrons keep the lattice bonded. C.…

Which substance is a good conductor of electricity in the solid state? A. Graphene B. Diamond C. Silicon dioxide D. Silicon

A section of a polymer containing three repeating units is shown. Which monomer was used to make this polymer? A. 1,1-dichloroethene B. Chloroethene C. 1,2-dichloroethene D. 3-chloroprop-1-ene

What are the oxidation states of the elements in $\ce{K2MnO4}$? A. K: +1, Mn: +6, O: −2 B. K: +1, Mn: +7, O: −2 C. K: +2, Mn: +4, O: −2 D. K: +1, Mn: +6, O: −1

What is the IUPAC name of the compound shown? A. 3-methylhexan-4-one B. 4-methylhexan-3-one C. 4-ethylpentan-3-one D. 2-ethylpentan-3-one

The first ionization energies of four elements with consecutive atomic numbers, A, B, C and D, are shown. An element X reacts with oxygen to form an acidic oxide. Which element could be X? A. A B. B C. C D. D

Which formula represents an amide? A. $\ce{CH3CH2NH2}$ B. $\ce{CH3CH2CONH2}$ C. $\ce{(C2H5)2NH}$ D. $\ce{H2NCH2CH2COOH}$

The potential energy profile of a reaction is shown. Which reaction has this energy profile? A. $\ce{Cl2(g) -> 2Cl(g)}$ B. $\ce{CaCO3(s) -> CaO(s) + CO2(g)}$ C. $\ce{N2O4(g) -> 2NO2(g)}$ D. $\ce{2Mg(s) + O2(g) -> 2MgO(s)}$

What is $\Delta H$, in kJ, in the energy cycle below? A. +20 - 165 B. +20 + 165 C. -20 + 165 D. -20 - 165

Which statement best describes an environmental consequence of using fossil fuels? A. The carbon dioxide released is completely absorbed by the oceans, so its concentration in the atmosphere does not change. B. Coal has a higher hydrogen to carbon ratio than…

Equal volumes of the gases $\ce{Q2}$ and $\ce{R2}$ are mixed in a sealed container and react until one of them is used up, forming the gas $\ce{QR2}$. The volume of $\ce{QR2}$ formed, measured under the same conditions, is 50 $\mathrm{cm^3}$.…

What volume of hydrogen, in $\mathrm{cm^3}$, is produced at STP when 0.810 g of aluminium reacts with an excess of hydrochloric acid? $\ce{2Al(s) + 6HCl(aq) -> 2AlCl3(aq) + 3H2(g)}$ Molar volume of an ideal gas at STP = 22.7 $\mathrm{dm^3\,mol^{-1}}$ A. 341 B.…

Nitrogen gas is reacted with excess hydrogen gas to produce ammonia. $\ce{N2(g) + 3H2(g) -> 2NH3(g)}$ The reaction of 28.0 g of $\ce{N2}$ with excess $\ce{H2}$ produces 25.5 g of $\ce{NH3}$. What is the percentage yield of $\ce{NH3}$? A. 25% B. 50% C. 75% D.…

The dotted line shows the volume of hydrogen produced when an excess of magnesium ribbon is added to 50 $\mathrm{cm^3}$ of 2.0 $\mathrm{mol\,dm^{-3}}$ hydrochloric acid. Which curve shows the volume of hydrogen produced when the same excess of magnesium ribbon…

Which reaction has the lowest activation energy? A. $\ce{HBr(g) -> H(g) + Br(g)}$ B. $\ce{2Cl(g) -> Cl2(g)}$ C. $\ce{CH4(g) + Cl(g) -> CH3(g) + HCl(g)}$ D. $\ce{HBr(g) -> H+(g) + Br-(g)}$

Which statement explains why a chemical equilibrium is described as dynamic? A. The forward and reverse reactions continue to take place at equal rates. B. The concentrations of the reactants and products keep changing until the reaction stops. C. The position…

In which reaction does water behave as a Brønsted–Lowry acid? A. $\ce{H2O(l) + HCl(g) -> H3O+(aq) + Cl-(aq)}$ B. $\ce{H2O(g) + SO3(g) -> H2SO4(l)}$ C. $\ce{2H2O(l) -> 2H2(g) + O2(g)}$ D. $\ce{H2O(l) + NH3(aq) -> NH4+(aq) + OH-(aq)}$

Which compounds are oxidized when heated with acidified potassium dichromate(VI) solution? I. $\ce{CH3CH2C(CH3)2OH}$ II. $\ce{(CH3)2CHCH2OH}$ III. $\ce{CH3CH(OH)CH3}$ A. I and II only B. I and III only C. II and III only D. I, II and III

Magnesium is a stronger reducing agent than lead. A voltaic cell is constructed using magnesium and lead electrodes dipped into solutions of their respective ions, $\ce{Mg^2+ (aq)}$ and $\ce{Pb^2+ (aq)}$, of equal concentrations. What is correct when the…

Which half-equation represents the reduction of sulfuric acid to sulfur dioxide in acidic solution? A. $\ce{H2SO4 + 2H+ + 2e- -> SO2 + 2H2O}$ B. $\ce{H2SO4 + 4H+ + 4e- -> SO2 + 2H2O}$ C. $\ce{H2SO4 + 2H2O -> SO2 + 6H+ + 2e-}$ D.…

Which radical is most likely to form when one covalent bond in bromochlorodifluoromethane, $\ce{CBrClF2}$, is broken by ultraviolet light in the upper atmosphere? A. •$\ce{CBrF2}$ B. •$\ce{CClF2}$ C. •$\ce{CBrClF}$ D. •$\ce{CBrClF2}$

Pent-2-ene undergoes a range of addition reactions. Which reagent and product are correctly matched? A. Reagent $\ce{H2}$, product pent-1-ene B. Reagent $\ce{Br2}$, product 2,3-dibromopentane C. Reagent $\ce{H2O}$, product pentan-1-ol D. Reagent $\ce{HBr}$,…