2022 TMJC H2 Chem Prelim P1 (QP)

2022 H2 Chem Prelim P1 (QP) Tampines Meridian Junior College 2022 JC2 Preliminary Examination H2 Chemistry 1 In which species are the numbers of protons, neutrons and electrons all different? A F− 9 19 B Na+ 11 23 C P15 31 D S2− 16 32 2 Beams of charged particles are deflected by an electric field. When a beam of protons passes through an electric field of constant strength, the angle of deflection is +12 . In another experiment under identical conditions, particle Y is deflected by an angle of – 4 . What could be the composition of particle Y? protons neutrons electrons 1 1 2 2 2 3 3 5 3 4 5 1 A 1, 2 and 3 B 1 and 2 C 1 only D 3 only 3 Use of the Data Booklet is relevant to this question. In which pair of compounds does the first molecule have a smaller bond angle than the second molecule? A BF3, NH3 B H2O, H2S C BeCl2, SCl2 D XeF4, SiCl4

2 2022 H2 Chem Prelim P1 (QP) Tampines Meridian Junior College 2022 JC2 Preliminary Examination H2 Chemistry 4 To produce decaffeinated coffee, pure liquid CO2 is sometimes used to extract caffeine from coffee beans. It was discovered that the solubility of caffeine greatly increased when a mixture of ethanol and liquid CO2 was used. Which interaction best explains why caffeine is more soluble in the ethanol -CO2 mixture as compared to liquid CO2? A instantaneous dipole - induced dipole interactions B permanent dipole - permanent dipole interactions C hydrogen bonding D dative covalent bond 5 Which graph does not share the same general shape as the other three graphs according to the ideal gas law for a fixed mass of gas with pressure p, volume V and temperature T in Kelvin? A p against 1 V (at constant T) B pV against p (at constant T) C pV against V (at constant T) D V T against T (at constant p)

3 Tampines Meridian Junior College 2022 JC2 Preliminary Examination H2 Chemistry [Turn over 6 Which statements about Group 2 elements are correct? 1 The charge density of cations increases down the Group. 2 The reducing strength of the elements increases down the Group. 3 The minimum temperature needed for the thermal decomposition of Group 2 carbonates increases down the Group. 4 The melting point of MgO is higher than CaO due to the higher polarising power of Mg2+. A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4 7 Due to its radioactive nature, the properties of astatine, At, have to be estimated based on its position in the Periodic Table. Which prediction concerning At or its compounds is correct? A Astatine is a weaker oxidising agent than iodine. B Astatine is a liquid at room temperature. C Astatine forms diatomic molecules which dissociate into atoms less readily than iodine molecules. D Hydrogen astatide has a higher decomposition temperature than hydrogen iodide. 8 Sodium thiosulfate (Na 2S2O3) is used in