2023 ASRJC H2 Chem Prelim P1 MS

ASRJC JC2 PRELIMS 2023 9729/01/H2 [Turn over ANDERSON SERANGOON JUNIOR COLLEGE 2023 JC2 PRELIMINARY EXAMINATION WORKED SOLUTION NAME:______________________________ ( ) CLASS: 23 /____ CHEMISTRY 9729/01 Paper 1 Multiple Choice 21 September 2023 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil Do not use staples, paper clips, glue or correction fluid. Write your name, class and register number on the Answer Sheet. There are thirty questions on this paper. Answer all questions. For each question, there are four possible answers, A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the separate Answer Sheet. Read the instructions on the Answer Sheet very carefully. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this booklet. The use of an approved scientific calculator is expected, where appropriate. Multiple Choice Answer Sheet Write your name, class and NRIC / FIN number, including the reference letter. Shade the NRIC / FIN number. Exam Title: JC2 PRELIM Exam Details: H2 Chemistry / Paper 1 Date: 21/09/2023

2 ASRJC JC2 PRELIMS 2023 9729/01/H2 1 In which species are the number of protons, neutrons and electrons all different? A 27 13 Al B 35 17 Cl – C 32 16 S2– D 39 19 K+ Ans D Work out the number for each of the options as follow. species 27 13 Al 35 17 Cl – 32 16 S2– 39 19 K+ no. of protons 13 17 16 19 no. of electrons 13 18 18 18 no. of neutrons 14 18 16 20 2 The ionisation energies, IE, of five elements are given in the table. second IE /kJ mol-1 third IE /kJ mol-1 fourth IE /kJ mol-1 B F Na Mg Al 2420 3370 4560 1450 1820 3660 6040 6940 7740 2740 25000 8410 9540 10500 11600 Which statement is correct? A The 2nd IE of F is higher than the 3 rd IE of Al because Al2+ has a higher nuclear charge than F+. B The 2nd IE of Mg is lower than 2 nd IE of Na because there is inter -electronic repulsion between the paired electrons in Mg+. C The 4th IE of B is higher than the 4th IE of Al because the electron to be removed from Al3+ is further away from the nucleus. D The successive IE of these elements increase because the shielding effect increases. Ans C F+: 1s22s22p4 Al2+: 1s22s22p63s1 Option A is incorrect. A l2+ has a higher nuclear charge than F + but the 3 rd electron that is removed from Al is also further away from nucleus than the 2 nd electron that is removed from F. Hence it experiences weaker electrostatic forces of attraction and the 3 rd ionisation energy of Al is lower than 2nd ionisation energy of F. Na+: 1s22s22p6 Mg+: 1s22s22p63s1 Option B is incorrect. The 2nd ionisation ener