2023 CJC H2 Chem Prelims P2 QP

[Turn over 9729/2 CJC JC2 Preliminary Examination 2023 CANDIDATE NAME CLASS 2T CHEMISTRY 9729/02 Paper 2 Structured Questions 28 August 2023 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name and class on all the work you hand in. 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 19 printed pages and 1 blank page. For Examiner’s Use Paper 1 30 Paper 2 Q1 /13 Q2 /12 Q3 /14 Q4 /14 Q5 /10 Q6 /12 75 Paper 3 80 Paper 4 55 OVERALL (100%) GRADE Catholic Junior College JC2 Preliminary Examination Higher 2

2 9729/2 CJC JC2 Preliminary Examination 2023 1 (a) Nitrogen and phosphorus are elements of Group 15 in the Periodic Table. (i) Explain why phosphorus has a larger atomic radius than nitrogen. ……………………………………………………………………………………….....……… ……………………………………………………………………………………….....……… ……………………………………………………………………………………….....……… ……………………………………………………………………………………….....……… ……………………………………………………………………………………………......[2] (ii) Nitrogen exists naturally as gaseous diatomic N≡N molecules whereas phosphorus is a solid and exists as P4 molecules comprising P–P single bonds. Suggest why phosphorus does not occur naturally as P≡P molecules. …….…………………………………………………………………………………………… ….……………………………………………………………………………………………... ………………………………………………………………………………………………[1] (b) Nitrate, NO 3–, and phosphate, PO 43–, are oxoanions of nitrogen and phosphorous respectively. (i) Draw dot–and–cross diagrams to show the bonding in NO 3– and PO43– ions. Hence, suggest the shape of each of these ions. [4] (ii) The 2s and 2p orbitals of nitrogen atoms can hybridise in the same way as the 2s and 2p orbitals of carbon atoms. With reference to your answer in (b)(i), state the hybridisation state of nitrogen in NO3–. ……………………………………………………………………………………………......[1] ion NO3– PO43– dot-and-cross diagram shape

3 9729/02/CJC JC2 Prelim