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 . Parti