Chemistry SL Paper 1A, May 2026

What is correct about the species $\ce{^{65}Zn^{2+}}$? A. 65 protons, 65 neutrons, 63 electrons B. 30 protons, 35 neutrons, 28 electrons C. 30 protons, 65 neutrons, 28 electrons D. 65 protons, 35 neutrons, 63 electrons

What is the maximum number of electrons that can occupy the 3rd main energy level in an atom? A. 6 B. 9 C. 18 D. 32

What is the correct electron configuration of the selenium atom? A. $1s^2 2s^2 2p^6 3s^2 3p^6 3d^{10} 4s^2 4p^4$ B. $1s^2 2s^2 2p^6 2d^{10} 3s^2 3p^6 4s^2 4p^4$ C. $1s^2 2s^2 2p^6 3s^2 3p^6 3d^{10} 4s^2 4p^6$ D. $1s^2 2s^2 2p^6 3s^2 3p^6 3d^{8} 4s^2 4p^6$

How many ions are present in 142 g of $\ce{Na2SO4}$? $M(\ce{Na2SO4}) = 142\ \mathrm{g\,mol^{-1}}$ A. 1 B. 3 C. $6.02 \times 10^{23}$ D. $1.81 \times 10^{24}$

What is the empirical formula of an alcohol with 60.0 % mass carbon and 13.4 % mass hydrogen? A. $\ce{C3H7}$ B. $\ce{C6H16O2}$ C. $\ce{C3H8O}$ D. $\ce{C2H6O}$

What is the correct formula of calcium phosphide? A. $\ce{Ca3P2}$ B. $\ce{Ca2P3}$ C. $\ce{CaPO4}$ D. $\ce{Ca3(PO4)2}$

Which properties are expected for the compound lithium bromide? A. Not soluble in water, low melting point, does not conduct electricity when solid, does not conduct electricity when molten B. Not soluble in water, low melting point, conducts electricity when…

What is the correct electron domain geometry and molecular geometry of $\ce{NCl3}$? A. Trigonal planar electron domain geometry, trigonal planar molecular geometry B. Tetrahedral electron domain geometry, trigonal pyramidal molecular geometry C. Trigonal…

Which species contains a coordination bond? A. $\ce{AlCl3}$ B. $\ce{PH3}$ C. $\ce{[NH4]+}$ D. $\ce{HCOO-}$

Which molecules are polar? I. $\ce{CHCl3}$ II. $\ce{CH2F2}$ III. $\ce{CF4}$ A. I and II only B. I and III only C. II and III only D. I, II and III

Which classification is correct? A. Alkali metal: rubidium; transition element: platinum; halogen: xenon; noble gas: bromine B. Alkali metal: rubidium; transition element: platinum; halogen: bromine; noble gas: xenon C. Alkali metal: platinum; transition…

Which oxide will react with water to produce the most basic solution? A. Potassium oxide B. Calcium oxide C. Sulfur trioxide D. Nitrogen dioxide

Which functional groups are present in this molecule? A. Secondary amine, hydroxyl, alkoxy B. Tertiary amine, alcohol, ketone C. Tertiary amine, hydroxyl, alkoxy D. Secondary amine, alcohol, ketone

Which of these molecules are isomers of each other? I. Butanal II. 2-methylpropan-1-ol III. Butan-2-ol A. I and II only B. I and III only C. II and III only D. I, II and III

Which classification is correct for this reaction? $\ce{2Mg(s) + CO2(g) -> 2MgO(s) + C(s)}$, heat is released A. Endothermic; temperature decreases; reactants more stable B. Exothermic; temperature decreases; products more stable C. Exothermic; temperature…

What is the sum of the coefficients when this equation is balanced with the smallest whole numbers? $\ce{\_CH3CH(CH3)CH2CH2CH3 + \_O2 -> \_CO2 + \_H2O}$ A. 20 B. 37 C. 47 D. 53

Given the following data: $\ce{CaO(s) + CO2(g) -> CaCO3(s)}$ $\Delta H = -p\ \mathrm{kJ}$ $\ce{2Ca(s) + O2(g) -> 2CaO(s)}$ $\Delta H = -q\ \mathrm{kJ}$ $\ce{2CaCO3(s) -> 2Ca(s) + 2C(s) + 3O2(g)}$ $\Delta H = +r\ \mathrm{kJ}$ What is the $\Delta H$ of the…

What is the effect of decreasing temperature on this Maxwell-Boltzmann energy distribution curve? A. The curve maximum is higher and to the left of A. B. The curve maximum is lower and to the right of A. C. The curve maximum is higher and to the right of A. D.…

Which substances will be present in the reaction vessel at the end of the reaction between 1.5 g of magnesium and 50.0 cm3 of 1.0 mol dm⁻³ hydrochloric acid? $\ce{Mg(s) + 2HCl(aq) -> MgCl2(aq) + H2(g)}$ A. $\ce{HCl(aq)}$, $\ce{MgCl2(aq)}$ B. $\ce{Mg(s)}$,…

What can be produced when pentanoic acid is reduced? A. Pentan-1-one B. Pentan-2-one C. Pentan-1-ol D. Pentan-2-ol

Which of these changes will increase the time taken for this reaction to go to completion? $\ce{Zn(s) + H2SO4(aq) -> ZnSO4(aq) + H2(g)}$ A. Increase the temperature B. Increase the concentration of $\ce{H2SO4}$ C. Use powdered zinc instead of zinc granules D.…

What can be deduced about this equilibrium reaction from these data? $\ce{A(g) + B(g) <=> 2C(g)}$ Temperature / K Equilibrium constant, K 280 400 340 40.0 A. It is an exothermic reaction and [products] < [reactants] at equilibrium. B. It is an endothermic…

Which change would shift the position of this equilibrium towards the products? $\ce{H2(g) + I2(g) <=> 2HI(g)}$ $\Delta H = -9\ \mathrm{kJ\,mol^{-1}}$ A. Increase pressure B. Decrease pressure C. Increase temperature D. Decrease temperature

Which statement about this reaction is correct? $\ce{2Cl2 + O2 -> 2Cl2O}$ A. Chlorine is the reducing agent. B. Oxygen is the reducing agent. C. Chlorine is reduced. D. Oxygen is oxidized.

Which of these reactions will occur spontaneously? I. $\ce{KI + Br2}$ II. $\ce{KBr + Cl2}$ III. $\ce{KCl + Br2}$ A. I and II only B. I and III only C. II and III only D. I, II and III

Which combination is correct for this cell, when nickel is more reactive than silver? A. Cathode: silver; anode: nickel; sign on cathode: -; sign on anode: + B. Cathode: nickel; anode: silver; sign on cathode: -; sign on anode: + C. Cathode: nickel; anode:…

What are the products of the electrolysis of molten lead(II) bromide? A. Product at cathode: lead; product at anode: bromine B. Product at cathode: lead; product at anode: bromide C. Product at cathode: bromine; product at anode: lead D. Product at cathode:…

Which equation is correct? A. $\ce{Cu(s) + H2SO4(aq) -> CuSO4(aq) + H2(g)}$ B. $\ce{Al(s) + H2SO4(aq) -> AlSO4(aq) + H2(g)}$ C. $\ce{Zn(s) + H2SO4(aq) -> ZnSO4(aq) + H2(g)}$ D. $\ce{Fe(s) + H2SO4(aq) -> FeSO4(aq) + H2(l)}$

Which equation shows the first species acting as an electrophile? A. $\ce{Br- + CH3CH2+ -> CH3CH2Br}$ B. $\ce{H2O + H+ -> H3O+}$ C. $\ce{CN- + CH3Br -> CH3CN + Br-}$ D. $\ce{AlCl3 + Cl- -> AlCl4-}$

What is the product of the reaction between hex-3-ene and steam, $\ce{H2O(g)}$? A. Hexan-3-ol B. Hexan-1-ol C. Hexanal D. Hexan-3-one