2024 TJC Prelims H1 P1 QP & Ans

1 8873 / TJC Prelims / 2024 TEMASEK JUNIOR COLLEGE 2024 JC2 PRELIMINARY EXAMINATION Higher 1 CHEMISTRY 8873/01 Paper 1 Multiple Choice 12 September 2024 1 hour Additional Materials: Multiple Choice Answer Sheet (OMS) Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. There are thirty questions In this paper. Answer all questions. For each question there are four possible answers A, B, C, 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. Write your name & Civics Group on the Answer sheet. Shade your index number in the appropriate boxes. 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. This document consists of 12 printed pages. Write your name and Civics Group Index number (refer to entry proof)

2 8873 / TJC Prelims / 2024 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 (OMS). 1 Which statement about the electrons in a ground state nitrogen atom is correct? A There are more electrons in s orbitals than there are in p orbitals. B Electrons are present in two different energy levels. C There is a pair of electrons in one of the p orbitals. D The occupied orbital of highest energy is spherical. Answer: A The electronic configuration of N is 1s22s22p3. A: Correct statement. There are 4 electrons in s orbitals and 3 electrons in p orbitals. B: Electrons are present in three different energy levels (1s, 2s and 2p). C: All the electrons in p orbitals are unpaired. D: The occupied orbital of highest energy level is 2p, which has a dumb-bell shape. 2 In an experiment, protons are deflected by an angle of +10°. In another experiment under identical conditions, particle X is deflected by an angle of –2.5°. What could be the composition of particle X? protons neutrons electrons A 4 4 5 B 2 2 3 C 2 2 1 D 1 2 2 Answer: B The angle of deflection is  charge/ mass. Since X is deflection in the opposite direction as proton, it has a negative charge, with charge/mass = ¼. charge mass Charge/ mass A -1 8 -1/8 B -1 4 -1/4 C +1 4 +1/4 D -1 3 -1/3

3 8873 / TJC Prelims / 2024 [Turn over 3 Which compound is composed of cation and anion that has the same number of electrons as each other? 1 Na2O 2 NaN3 3 NH4F 4 NaCl A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4 Answer: A Cation Number of e- Anion Number of e- 1 Na+ 11 – 1 = 10 O2- 8 + 2 = 10 2 Na+ 10 N3- 3(7) + 1 = 22 3 NH4+ 7 + 4 – 1 = 10 F- 9 + 1 = 10 4 N