2021_TJC_H2Chemistry Prelim_P2

1 [Turn over DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 9729 / TJC Prelim / 2021 CANDIDATE NAME CIVICS GROUP / CENTER NUMBER S INDEX NUMBER CHEMISTRY 9729/02 Paper 2 Structured Questions 24 August 2021 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your Civics Group, centre number, index number and name in the spaces at the top of this page. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. 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. This document consists of 20 printed pages. For Examiner’s Use 1 2 3 4 5 Total PRELIMINARY EXAMINATIONS HIGHER 2

2 [Turn over DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 9729 / TJC Prelim / 2021 Answer all the questions in the spaces provided. 1 (a) Excited states can be studied to gain information about the energies of orbitals that are unoccupied in an atom’s ground state. The excited state of an element, Q, is represented by the electronic configuration 1s22s22p63s23p63d44s24p1. (i) Identify the element Q. [1] (ii) Draw the energy level diagram showing the electronic configuration of element Q in its ground state. [2]

3 [Turn over DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 9729 / TJC Prelim / 2021 (iii) The arrangement of electrons in the d orbitals depends on the spin states of complexes. The following diagram shows how the d orbitals are split in an octahedral environment for the ion Qn+. In a ‘high spin’ state, the electrons occupy all the d orbitals singly, before starting to pair up in the lower energy d orbitals. In a ‘low spin’ state, the lower energy d orbitals are filled first, by pairing up if necessary, before the higher energy d orbitals are used. Use diagrams like the one given to show the electronic configuration of a ground state Q2+ ion in low spin state.