2023 TMJC H2 Chem Prelim P1 (QP)

2023 H2 Chem Prelim P1 (QP) 2 Use of Data Booklet is relevant to this question. On losing an electron, w hich particle would have the greatest number of unpaired electrons? A C– B Fe3+ C Ti2+ D P 3 Particle X has a charge of +1 and a proton number, n. Particle Y has a proton number of (n+1) and is isoelectronic with X. Which of the following statements correctly describes X and Y? A X and Y are isotopes. B The atoms of X and Y have the same electronic configurations. C Y has a charge of +1 and same charge density as that of X. D Y has a charge of +2 and smaller ionic radius than X. 4 The Valence Shell Electron Pair Repulsion (VSEPR) Theory is used to predict the shapes of molecules or polyatomic ions. Which of the following pairs of species are planar? A F2O and PF5 B SO32– and ClF3 C BrF4– and NO2 D ICl5 and CO2 1 A sample of boron contains two naturally occurring isotopes, 10B and 11B. This sample has a relative atomic mass value of 10.75. What is the percentage of the isotope 11B in the sample? A 20 B 25 C 75 D 80

2 2023 H2 Chem Prelim P1 (QP) Tampines Meridian Junior College 2023 JC2 Preliminary Examination H2 Chemistry 5 Which of these phenomena cannot be explained by hydrogen bonding? 1 NH4Br has a higher boiling point than HBr. 2 Ice is less dense than water. 3 Dimerisation of NO2 to form N2O4. 4 Ethanoic acid forms dimers which dissolved in organic solvents A 1, 3 and 4 only B 1 and 3 only C 2 and 4 only D 1 only 6 A 2.50 dm3 vessel containing ethane gas at a pressure of 1. 50 x 105 Pa is connected to a 7.50 dm 3 vessel containing methane gas at a pressure of 2. 50 x 10 5 Pa. The gases are allowed to mix freely. The temperature of the system is then raised from 100 °C to 350 °C. (Note that there is no chemical reaction between both gases) What is the final pressure of the system? A 2.25 x 105 Pa B 3.76 x 105 Pa C 6.68 x 105 Pa D 7.88 x 105 Pa 7 Which statements concerning only the elements in the third period, sodium to argon, are correct? 1 The element with the highest pH for its chloride in water is sodium. 2 The element with the highest electrical conductivity is aluminium. 3 The element with the highest melting point for its oxide is silicon. 4 The element that has eight atoms in its molecule is sulfur. A 1 and 4 only B 2 and 3 only C 1, 2 and 4 only D 1, 3 and 4 only

3 [Turn over Tampines Meridian Junior College 2023 JC2 Preliminary Examination H2 Chemistry 8 The equations for three reactions are given below: Cl2(g) + H2S(g) → 2HCl(g) + S(s) SO2(g) + 2H2S(g) → 2H2O(l) + 3S(s) Cl2(g) + 2H2O(l) + SO2(g) → 2HCl(aq) + H2SO4(aq) Which is the correct order of strength of the three reacting gases as oxidising agents? Strongest Weakest A Cl2 SO2 H2S B Cl2 H2S SO2 C H2S SO2 Cl2 D SO2 H2S Cl2

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