NASS Chem Prelim P1 P2 with ans

NAS/2024/Prelim/4E/Chemistry/6092/01 3 1 In which change do the particles move further apart? 1 A gas is heated from 0 °C to 25 °C. 2 Pressure is applied to a gas at a constant temperature. 3 Steam condenses to form water. 4 Water evaporates at room temperature. A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4 2 A student accidentally mixed 50 cm3 of oil and 5 g of solid calcium nitrate. Which sequence of procedures would allow him to obtain a pure sample of solid calcium nitrate most easily? A dissolve in ethanol  filtration  crystallisation B dissolve in water  filtration C dissolve in water  separating funnel  crystallisation D simple distillation  crystallisation 3 Which mixture of gases would not change the colour of damp blue litmus paper? A carbon dioxide and oxygen B chlorine and nitrogen C hydrogen and ammonia D neon and hydrogen chloride 4 The rate of diffusion of two gases is measured at different temperatures but at constant pressure. Which would diffuse most quickly? A argon at 15 °C B argon at 40 °C C carbon dioxide at 15 °C D carbon dioxide at 40 °C

NAS/2024/Prelim/4E/Chemistry/6092/01 4 5 A student follows the rate of the reaction between marble chips, CaCO3, and dilute hydrochloric acid. CaCO3 + 2HCl → CaCl2 + CO2 + H2O Which diagrams show apparatus that is suitable for this experiment? 1 2 3 4 A 1 and 3 B 2 and 3 only C 2 and 4 D 2, 3 and 4 6 The following observations were made by reacting three salt solutions with excess aqueous sodium hydroxide and excess aqueous ammonia. solution 1 2 3 add excess aqueous sodium hydroxide colourless solution colourless solution white ppt add excess aqueous ammonia white ppt colourless solution colourless solution Which cations are present in each solution? 1 2 3 A Al3+ Ca2+ Zn2+ B Al3+ Zn2+ Ca2+ C Ca2+ Zn2+ Al3+ D Zn2+ Al3+ Ca2+

NAS/2024/Prelim/4E/Chemistry/6092/01 5 7 Solution Y contains a mixture of flavourings. Solution Y and four other solutions, A, B, C and D, are analysed by chromatography. Chromatogram 1 shows the result of the experiment. Chromatogram 2 shows the results of Chromatogram 1 when sprayed with a locating agent. Which solution contains the same mixture of flavourings as solution Y? 8 Substances can be classified as elements, compounds or mixtures. Which underlined substance best represents a mixture? A black powder burns in air to form a colourless gas as the only product B green powder leaves a black residue and a colourless gas upon heating C grey solid that conducts electricity D white solid that melts from 56 °C to 58 °C 9 Boron oxide has the structure shown. How many valence electrons in a molecule of boron oxide are not involved in bonding? A 0 B 10 C 12 D 22

NAS/2024/Prelim/4E/Chemistry/6092/01 6 10 An isotope of element Q can be written as . Particle R has four more neutrons, one more proton and one more electron than the isotope of Q. Particle S has two more neutrons, same number of protons and one less electron than the isotope of Q. What represents R and S? R S A B C D 11 The structure and melting points of two compounds are shown below. name silicon dioxide poly(propene) structure melting point 1600 °C 160 °C Which statement about the compounds is correct? A Poly(propene) has a low melting point due to the weak covalent bonds between atoms. B Silicon dioxide has a high melting point due to the numerous strong covalent bonds between atoms. C Silicon dioxide has a high melting point due to the strong intermolecular forces of attraction. D Both compounds have a similar three-dimensional arrangement to diamond. 12 Which substance conducts electricity using mobile electrons in the liquid state? A copper B diamond C magnesium chloride D methane 32 16 Q 37 17 R– 37 17 R 34 16 S+ 34 16 S– 37 17 R– 34 16 S– 37 17 R 34 16 S+

NAS/2024/Prelim/4E/Chemistry/6092/01 7 13 The fertiliser ammonium nitrate (NH 4NO3, Mr = 80) is manufactured from ammonia (Mr = 17) by a two-stage process. stage 1 NH3 + 2O2  HNO3 + H2O stage 2 HNO3 + NH3  NH4NO3 What is the maximum mass of ammonium nitrate fertiliser that can be made if a total of 17 tonnes of ammonia are available for both stage 1 and stage 2? A 34 tonnes B 40 tonnes C 80 tonnes D 97 tonnes 14 Aerials in portable radios are made of a mixture of the oxides of calcium and iron known as ‘ferrite’. It contains 18.5% calcium and 51.9% iron by mass. Which is the empirical formula of ‘ferrite’? A CaFe2O B CaFe2O4 C Ca2FeO2 D Ca4Fe2O 15 A chemist adds 8.0 g of pure calcium oxide to an excess of dilute nitric acid. CaO + 2HNO3  Ca(NO3)2 + H2O 12.6 g of pure, dry calcium nitrate crystals is formed. What is the percentage yield of calcium nitrate? A 53.8% B 63.5% C 67.1% D 76.0% 16 Which quantity is the same for one mole of ethanol and one mole of ethane? A mass B number of atoms C number of molecules D volume at room temperature and pressure

NAS/2024/Prelim/4E/Chemistry/6092/01 8 17 Hydrated nickel(II) sulfate crystals have the formula NiSO4•5H2O in which one mole of nickel(II) sulfate is combined with 5 moles of water. What is the percentage by mass of oxygen in hydrated nickel(II) sulfate crystals? [A r: Ni, 59; S, 32; O, 16; H,1] A B C D 18 A simple cell was set up to light up a bulb as shown in the diagram below. What should X, Y and Z be for the bulb to light up the brightest? X Y Z A magnesium iron dilute ethanoic acid B magnesium iron dilute sulfuric acid C magnesium zinc dilute ethanoic acid D magnesium zinc dilute sulfuric acid 19 Aqueous silver nitrate is electrolysed using a positive silver electrode and a negative carbon electrode. Which row shows the ionic equations at each electrode? positive electrode negative electrode A Ag(s)  Ag+(aq) + e– 2H+(aq) + 2e–  H2(g) B 4OH–(aq)  O2(g) + 2H2O(l)+ 4e– Ag+(aq) + e–  Ag(s) C 4OH–(aq)  O2(g) + 2H2O(l)+ 4e– 2H+(aq) + 2e–  H2(g) D Ag(s)  Ag+(aq) + e– Ag+(aq) + e–  Ag(s) 5 x 16 155 x 100 7 x 16 245 x 100 9 x 16 155 x 100 9 x 16 245 x 100

NAS/2024/Prelim/4E/Chemistry/6092/01 9 20 Three different compounds are electrolysed. Which experiments produce a gas at the cathode? A 1 only B 2 only C 1 and 3 D 2 and 3 21 The complete combustion of ethane is an exothermic reaction. Which statement about the reaction is correct? A The activation energy is greater than the energy taken in when the bonds are formed. B The activation energy is greater than the energy released when the bonds are formed. C The activation energy is less than the energy taken in when the bonds are formed. D The activation energy is less than the energy released when the bonds are formed. 22 The equation for the combustion of hydrogen is shown. 2H2 (g) + O2 (g)  2H2O (g) The bond energies of the bonds are given in the following table. bond bond energy (kJ/mol) H–H 436 O–H 463 O=O 498 What is the enthalpy change of this reaction? A –482 kJ/mol B –444 kJ/mol C +444 kJ/mol D +482 kJ/mol

NAS/2024/Prelim/4E/Chemistry/6092/01 10 23 The equation and the energy profile diagram for the reversible reaction in the Haber process are shown. Which statement about the reactions is correct? A The activation energy for the forward reaction is y – x. B The activation energy for the reverse reaction is x. C The enthalpy change for the reverse reaction is positive. D The enthalpy change decreases when a catalyst is used. 24 A student adds excess carbonate to 100 cm 3 of 0.1 mol/dm3 hydrochlori