2024 Prelims NYJC H2 Chem P2 (QP)

[Turn over NANYANG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CLASS CHEMISTRY 9729/02 Paper 2 Structured 9 September 2024 2 hours Candidates answer on the Question Paper Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name and class in the spaces at the top of this page. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, glue or correction fluid. Answer all questions in the spaces provided on the Question Paper. The use of an approved scientific calculator is expected, where appropriate. A Data Booklet is provided. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use 1 /12 2 /7 3 /6 4 /6 5 /11 6 /11 7 /22 Total /75 This document consists of 21 printed pages and 2 blank pages. H

2 H2 Chemistry 9729/02 NYJC J2/24 PX [Turn Over For Examiner's Use Answer all questions in the space provided. 1(a) The Periodic Table usually shows hydrogen on its own and not a member of a group. (i) Suggest why the element hydrogen could be placed at the top of Group 1. ......................................................................................................................... ..................................................................................................................... [1] (ii) Suggest why the element hydrogen is not placed at the top of Group 1, in terms of • its structure • one physical property related to its structure ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... ..................................................................................................................... [2] The trihydrogen complex cation, H 3+, was first discovered in 1911 when J.J . Thomson was performing his cathode ray tube experiments. In 1989, H 3+ was detected in the ionosphere of Jupiter. H3+ is mainly found in interstellar space where there is high cosmic radiation. In the presence of high energy gamma radiation, hydrogen gas can lose an electron to form H 2+, which then reacts with molecular hydrogen to form H3+. H2 → H2+ + e− H2+ + H2 → H3+ + H (b) Describe and explain how the behaviour of beams of the ions H2+, H3+ and electrons differ in an electric field. .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... ................................................................................................................................ [2]

3 H2 Chemistry 9729/02 NYJC J2/24 PX [Turn Over For Examiner's Use (c) Given that hydrogen can exist as isotopes 1H, 2H and 3H, complete Table 1.1. Table 1.1 number of protons number of neutrons number of electrons 2H 1H2+ 3H3+ [3] (d) Describe the reactions, if any, of the chlorides NaCl, AlCl3 and PCl5 with water. Write equations for all the reactions that occur, and suggest the pH of the resulting solutions. Relate the reactivity of these chlorides to their structure and bonding. .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... ................................................................................................................................ [4] [Total: 12]

4 H2 Chemistry 9729/02 NYJC J2/24 PX [Turn Over For Examiner's Use 2 Ozone, O 3, is a non -linear molecule present in the Earth’s upper atmosphere. It absorbs ultraviolet radiation from the Sun and so protects living organisms from this type of radiation. (a) (i) Draw the dot-and-cross diagram for the ozone molecule. [1] (ii) State one harmful consequence to a person of increased exposure to ultraviolet radiation. ....................................................