2021 YIJC Prelim P1 Solution

©YIJC [Turn over YISHUN INNOVA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CG INDEX NO CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Data Booklet 9729/01 16 September 2021 1 hour MCQ Answer Key: 1 2 3 4 5 6 7 8 9 10 D B B A C D C B C C 11 12 13 14 15 16 17 18 19 20 D A A C D A B B C D 21 22 23 24 25 26 27 28 29 30 A A A D B D C D A B

2 ©YIJC [Turn over 1 A 1.00 g alkane D was burnt in an excess of oxygen, and the gases that were produced were first passed through a U-tube containing phosphorus pentoxide and another U-tube containing NaOH(s) as shown in the diagram. The phosphorus pentoxide U -tube increased in mass by 1.55 g, and the NaOH(aq) bottle increased in mass by 3.03 g. All volumes were measured at room temperature and pressure. What is the molecular formula of the alkane D? A CH4 B C2H5 C C2H6 D C4H10 Answer: D Amount of H atoms = 2  0.0861 = 0.1722 mol Amount of C atoms = 0.0689 mol Ratio of H : C = 0.1722 0.0689 = 2.4992 : 1 = 5 : 2 Since the molecular formula of an alkane is CnH2n+2, the molecular formula of alkane D must be C4H10. 2 Use of the Data Booklet is relevant to this question. What do the ions 36S2 and 37Cl have in common? A Both ions have more electrons than neutrons. B Both ions have the same electronic configuration. C Both ions contains the same number of nucleons. D 36S2 has a smaller angle of deflection than 37Cl in an electric field. Answer: B Option A: 36S2 has 16 protons, 20 neutrons and 18 electrons, 37Cl has 17 protons, 20 neutrons and 18 electrons. Option B: Both ions are 1s2 2s2 2p6 3s2 3p6 Option C: 36S2 has 16 protons + 20 neutrons = 36 nucleons 37Cl has 17 protons + 20 neutrons = 37 nucleons Option D: angle of deflection = charge/mass, 36S2= 0.0556 > 37Cl , 0.0270 Oxygen gas used oxygen gas Phosphorous pentoxide NaOH(s) pellets Alkane D

3 ©YIJC [Turn over 3 Boyle’s law states that at constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure. Which of the following statements shows application of Boyle’s law? 1 Human lungs, inhalation and exhalation. 2 Spraying paint from a can. 3 Working of hot air balloon. A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 1 only Answer: B Option 1: correct. While inhaling, the lungs are filled with air; therefore, they expand. The volume increases hence, the pressure level goes down. Similarly, when the lungs are evacuated of air, they shrink; therefore, the volume reduces and the pressure increases. Option 2: correct. When the top of the can is pressed, the volume inside the can gets reduced and the paint is