H1 Chem P1_SAJC_2024_Ans

1 ST ANDREW’S JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATIONS HIGHER 1 CANDIDATE NAME CLASS 2 3 S CHEMISTRY Paper 1 Multiple Choice Candidate answer on the Optical Answer Sheet Additional Materials: Data Booklet 8873/01 11 September 2024 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. 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 Optical Answer Sheet. 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 13 printed pages (including this cover page).

2 1 Oxygen exist as two isotopes; 16O and 18O respectively. Which of the following particles contain more neutrons than protons and more protons than electrons respectively? 1 12C18O32– 2 1H316O+ 3 14N18O+ A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 3 only Ans: D Option 1 is wrong because the particle have a negative charge, implying that the number of electrons is more than the number of protons. Option 2 is wrong because 16O has similar number of protons and neutrons and 1H has more proton than neutron even though there is more proton than electron due to the positive charge. Option 3 is correct because 18O in N 18O+ has 2 more neutrons than protons, and 1 more proton than electron. 2 The first seven successive ionisation energies for element X are as shown. X is found in Period 3. 1st 2nd 3rd 4th 5th 6th 7th Ionisation energy / kJ mol–1 1010 1900 2900 5000 6300 21300 25400 Which compound can be formed using X? A XO B XO2 C XO3 D X4O10 Ans: D There is a large jump in ionisation energy from 5th to 6th, which implies that the 6th electron comes from an inner shell that is closer to nucleus and will experience stronger nuclear attraction. Hence, X has 5 valence electrons and is from Group 15. As a period 3 element, it is able to form X4O10 (ie P4O10).

3 3 Use of the Data Booklet is relevant to this question. Tl81 204 can undergo natural radioactive decay, where one of its electrons enters the nucleus to change a proton into a neutron, to form a new element X. When X is put in an ionisation chamber, it emits a high energy -particle (which is a 4He nucleus). What is the identity of the element X and the path of the emitted -particle in an electric field? X Deflection Path A X80 204 I B X82 204 II C X80 205 I D X82 205 II Ans: A Based on the radioactive decay, the proton number will drop by 1. But however, the nucleon number will remain the same as there is now 1 more neutron. Hence, X is X80 204 . Angle of deflection α |q/m|