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 hydroxide required to react completely with V dm3 of dilute sulfuric acid? A 13 V dm3 B 23 V dm3 C 32 V dm3 D 43 V dm3 11 Which of the following involves the largest number of electrons for complete discharge during electrolysis? A 3 mol of P3- ions B 4 mol of Al3+ ions C 5 mol of O2- ions D 8 mol of Na+ ions

NAS/2023/Prelim/4E/Chemistry/6092/01 6 12 Which statement best describes the mechanism of a hydrogen-oxygen fuel cell? A Electricity is used to provide heat energy. B Electricity is used to generate hydrogen and oxygen. C Hydrogen ions react with hydroxide ions to generate electricity. D Hydrogen and oxygen undergo redox reactions to generate electricity. 13 The diagram shows the apparatus used for refining a sample of impure copper. The loss in mass of the positive electrode was 50 g and the gain in mass of the negative electrode was 45 g. What was the percentage purity of this sample of copper? A 5.0 % B 10.0 % C 90.0 % D 95.0 % 14 The diagram shows the electrolysis of concentrated and dilute aqueous sodium chloride using inert electrodes. Gases are produced and collected in each of the test-tubes W, X, Y and Z. Which statement is correct? A Approximately equal volumes of gas are produced and collected in test-tubes Y and Z. B Oxygen gas is collected in test-tube W. C Three different gases are produced in the experiment. D Two different gases are produced in the experiment. pure copper impure copper aqueous copper(II) sulfate concentrated sodium chloride dilute sodium chloride

NAS/2023/Prelim/4E/Chemistry/6092/01 7 15 Methane burns in oxygen to form carbon dioxide and water. The energy profile diagram is shown. Which statement about bond breaking and forming is correct? A The energy released in forming bonds is labelled x. B The energy released in breaking bonds is equal to z. C The energy released in breaking bonds is less than the energy absorbed in forming bonds. D The energy released in forming bonds is more than the energy absorbed in breaking bonds. 16 The formation of liquid water from hydrogen and oxygen may occur in three stages. 1 2H2(g) + O2(g) à 4H(g) + 2O(g) 2 4H(g) + 2O(g) à 2H2O(g) 3 2H2O(g) à 2H2O(l) Which stages(s) are endothermic? A 1, 2 and 3 B 1 only C 2 only D 3 only 17 In which reaction is substance P reduced? A Acidified potassium manganate(VII) is decolourised on addition to an aqueous solution of P. B Adding aqueous potassium iodide to an aqueous solution of P gives a brown colour. C P à P2+ + 2e– D PO– + O2 à PO3–

NAS/2023/Prelim/4E/Chemistry/6092/01 8 18 Dilute sulfuric acid was reacted with 24.0 g of powdered magnesium at room temperature in two experiments, experiment 1 and experiment 2. Mg(s) + H2SO4(aq) à MgSO4(aq) + H2(g) In experiment 1, 100 cm3 of 1.0 mol/dm3 sulfuric acid was used. In experiment 2, 50 cm3 of 2.0 mol/dm3 sulfuric acid was used. During each experiment the volume of hydrogen produced is measured. The results are plotted on a graph. Which graph is correct? Refer to the key for the graphs. A B C D 19 Which row shows the pH values for 0.1 mol/dm3 solutions of ammonia, hydrochloric acid, sodium chloride and sodium hydroxide? pH values NH3 HCl NaCl NaOH A 1 7 13 11 B 7 1 11 13 C 11 1 7 13 D 13 11 7 1

NAS/2023/Prelim/4E/Chemistry/6092/01 9 20 Three separate mixtures of a solution and a solid are made. The mixtures are warmed. In which mixture does a gas form? NaOH(aq) and NH4Cl(s) H2SO4(aq) and NH4Cl(s) H2SO4(aq) and Mg(s) A P P O B P O P C O P O D O O P 21 Given a supply of lead(II) carbonate, copper(II) carbonate, dilute nitric acid and aqueous sodium hydroxide, how many different salt(s) could be prepared? A 1 B 2 C 3 D 4 22 Which statement about oxides is correct? A A basic oxide is an oxide of a non-metal. B Acidic oxides contain ionic bonds. C Amphoteric oxides contain a metal. D Basic oxides are always gases. 23 The elements in Group I of the Periodic Table show trends in both their reactivities and their melting points. Rubidium is in Group I. Which statement about rubidium is correct? A It has a higher melting point than potassium. B It reacts with water to produce an acidic solution. C It reacts with water to produce oxygen gas. D It is more reactive than potassium. 24 Aqueous bromine is added to aqueous sodium chloride. Which statement is correct? A Bromine is oxidised and chloride ions are reduced. B Bromine is reduced and chloride ions are oxidised. C Neither oxidation nor reduction takes place. D Sodium ions are oxidised. 25 Which property of aluminium suggests it is not a transition metal? A conducts electricity B high melting point C low density D malleable

NAS/2023/Prelim/4E/Chemistry/6092/01 10 26 Which metal can react rapidly with steam but reacts only very slowly with cold water? A copper B iron C magnesium D sodium 27 Metal P is more reactive than metal Q wh