YIJC 2025 Prelim P2 Suggested Solutions (for exchange)_H2 Chem

YISHUN INNOVA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME Suggested Solutions CG INDEX NO CHEMISTRY Paper 2 Structured Questions Candidates answer on the Question Paper. Additional Materials: Data Booklet 9729/02 1 September 2025 2 hours READ THESE INSTRUCTIONS FIRST Write your name, class and index number 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 28 printed pages. For Examiner’s Use 1 / 18 2 / 24 3 / 17 4 / 16 Penalty units significant figures Overall / 75

2 ©YIJC 9729/02/JC2/PE/2025 [Turn over Answer all the questions in the spaces provided. 1 (a) Compounds A, B and C are shown in order of increasing basicity. Explain this order. C is most basic as the N is attached to an electron donating alkyl group which increases the electron density on the N atom and hence increasing the availability of lone pair of electrons to accept H+. In compound B, there is delocalisation of lone pair of electrons on N atom into the benzene ring. Hence this decreases the availability of lone pair of electrons on the N atom to accept H+, making compound X less basic than C. A is an amide and is neutral because the lone pair of electrons on the N atom is delocalised into the electron -withdrawing C=O group , hence unavailable to accept a H + ion. Hence compound A is the least basic amongst the three compounds. [3] (b) Amides can be found in many drugs such as paracetamol and procainamide. Procainamide can be used for the treatment of cardiac arrhythmias. procainamide Predict the products obtained when procainamide undergoes reaction with hot, dilute H2SO4. and [2]

3 ©YIJC 9729/02/JC2/PE/2025 (c) Compound J can be synthesised by the following route in Fig. 1.1, with all the carbon atoms coming from compound E. Fig. 1.1 • Compound E does not react with NaOH(aq) but reacts with Na to give a gas that extinguishes a lighted splint with a ‘pop’ sound. • Compound H is soluble in dilute HCl and can also be obtained from the reaction of compound K with LiAlH4. K • Compound J is neutral and is a cyclic molecule. (i) Draw the structure of compounds E to H, and J. E F G H J [5] (ii) State the reagents and conditions for steps 2 and 4.