2023 NASS Chem Prelims P1

NAS/2023/Prelim/4E/Chemistry/6092/01 3 NGEE ANN SECONDARY SCHOOL PRELIMINARY EXAMS 2023 CHEMISTRY PAPER 1 1 A student accidentally mixed 50 cm3 of water with 50 cm3 of oil. Which method would allow him to obtain 25 cm3 of the oil most easily? A evaporation B filtration C fractional distillation D using a separating funnel 2 A gas is allowed to diffuse across a narrow hollow tube as shown below. Which of the following changes will increase the rate of diffusion of the gas through the tube? I place the tube vertically II increase the temperature of the gas from 25 oC to 45 oC III lowering the pressure from 1 atm to 0.5 atm IV replacing the nitrogen gas with carbon monoxide gas A I and II B II only C II and III D II and IV 3 Which of the following statement is correct? A When a liquid reaches its boiling point, it becomes a gas. This process is called evaporation. B When a gas condenses, it becomes a liquid and energy is lost to the surroundings. C When a solid changes directly to a gas, the process is called deposition. D When a solid melts, the particles get further apart and have less energy. 4 An aqueous solution contains the same amount of Al3+(aq) and of Cu2+(aq). Aqueous ammonia is added until in excess. After shaking, the mixture is filtered. What would be left on the filter paper? A a white solid and a blue solid B a white solid C a blue solid D no solid residue gas narrow hollow tube

NAS/2023/Prelim/4E/Chemistry/6092/01 4 5 An aqueous solution of a compound, N, undergoes the following reactions. N + aqueous sodium hydroxide + nitric acid + aqueous silver nitrate blue precipitate yellow precipitate What is N? A copper(II) carbonate B copper(II) chloride C copper(II) iodide D copper(II) nitrate 6 The element X and Y form an ionic compound XY3. Given that X has 56 particles in the nucleus, which row shows the correct composition of an ion of X? number of protons number of neutrons number of electrons A 26 30 23 B 26 30 26 C 30 26 30 D 30 26 33 7 The ‘dot-and-cross’ diagrams for four compounds are shown. Only outer shell electrons are shown. Which diagram is correct? A B C D

NAS/2023/Prelim/4E/Chemistry/6092/01 5 8 An oxide of element Z has the following properties. • conducts electricity in molten but not in solid • insoluble in water • used as a refractory material Which electronic configuration is likely to be Z? A 2, 8, 1 B 2, 8, 2 C 2, 8, 4 D 2, 8, 7 9 Nitrogen monoxide gas from motor vehicles exhausts can be removed by injecting a stream of ammonia gas into the exhaust vapour. The reaction is shown below. 6 NO(g) + 4 NH3(g) à 5 N2(g) + 6 H2O (g) What volume of ammonia gas is needed to completely react with 3600 cm3 of nitrogen monoxide? A 600 cm3 B 1200 cm3 C 2400 cm3 D 5400 cm3 10 0.2 mol/dm3 of dilute sulfuric acid is titrated with 0.3 mol/dm3 aqueous potassium hydroxide. What is the volume of aqueous potassium hy