2025 ASRJC Prelim H2Chem P1 QP

9729/01/H2 [Turn over ANDERSON SERANGOON JUNIOR COLLEGE 2025 JC2 PRELIMINARY EXAMINATION NAME:______________________________ ( ) CLASS: 25 /____ CHEMISTRY 9729/01 Paper 1 Multiple Choice 2 September 2025 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, class and register number on the Answer Sheet. 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 Answer Sheet. Read the instructions on the Answer Sheet very carefully. 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 15 printed pages and 1 blank page. Multiple Choice Answer Sheet Write your name, class and NRIC / FIN number, including the reference letter. Shade the NRIC / FIN number. Exam Title: JC2 PRELIM Exam Details: H2 Chemistry / Paper 1

2 9729/01/H2 1 Sodium azide, NaN3 is an explosive used to inflate airbags in cars when they crash. It consists of positive sodium ions and negative azide ions. What are the number of electrons in the sodium ion and the azide ion? sodium ion azide ion A 10 20 B 10 22 C 12 20 D 12 22 2 The graph shows the variation of the first ioni sation energy with proton number for some elements. The letters used are not the actual symbols for the elements. Which statement about the elements is correct? A P and X are in the same period in the Periodic Table. B The general increase from Q to X is due to increasing atomic radius. C The small decrease from R to S is due to decreased shielding. D The small decrease from U to V is due to repulsion between paired electrons. first ionisation energy / kJ mol–1 proton number

3 9729/01/H2 [Turn over 3 The table identifies the shape and polarity of four molecules. Which row is correct? molecule molecular shape polarity A boron trichloride trigonal pyramidal polar B nitrogen trichloride trigonal planar non-polar C sulfur dioxide bent polar D trichloromethane tetrahedral non-polar 4 The element tin exists in two forms, grey tin and white tin. Some properties of grey tin and white tin are shown. grey tin white tin boiling point 2543 oC 2533 oC electricial conductivity none in solid or liquid good in solid and liquid malleability brittle malleable Which structural change might take place when grey tin changes to white tin? A giant covalent to giant ionic B giant covalent to giant metallic C giant ionic to giant covalent D giant ionic to giant metallic

4 9729/01/H2 5 0.01 mol of K IOn reacts with 0.05 mol of K I stoichiometrically to produce I2 under acidic conditions. In this reaction, all the iodine containing reactants were converted to I2. What is the value of n? A 1 B 2 C 3 D 4 6 X and Y are two different samples of the same ideal gas. Given that X contains a higher mass than Y, which graph shows the correct ideal gas relationship for the two samples of gas? (T is measured in K.) A B C D V T Y X V T X Y V T X Y X Y T V

5 9729/01/H2 [Turn over 7 A student mixes 25.0 cm 3 of 0.350 mol dm –3 sodium hydroxide solution with 25.0 cm 3 of 0.350 mol dm –3 hydrochloric acid. The temperature increases by 2.5 °C. No heat is lost to th e surroundings. The final mixture has a specific heat capacity of 4.2 J g–1 K–1. What is the molar enthalpy change for the reaction? A –150 kJ mol–1 B –60 kJ mol–1 C –30 kJ mol–1 D –0.15 kJ mol–1 8 Silane, SiH4, exists as a gas at standard temperature and pressure. Hess’ Law can be used to calculate the average Si–H bond energy in gaseous SiH4. Which information is needed to perform the calculation? A ∆Hoatomisation(Si), ∆Hocombustion(H2), ∆Hoformation(SiH4) B ∆Hoatomisation(Si), ∆Hoatomisation(H), ∆Hoformation(SiH4) C ∆Hoatomisation(H), ∆Hocombustion(Si), ∆Hocombustion(SiH4) D ∆Hocombustion(Si), ∆Hocombustion(H2), ∆Hoformation(SiH4) 9 Group 2 hydroxides undergo thermal decomposition in a similar fashion to Group 2 carbonates. Barium hydroxide undergoes decomposition as shown in the equation below: Ba(OH)2(s) → BaO(s) + H2O(g) H > 0 Which statements about this reaction are correct? 1 The Gibbs free energy change can be positive or negative depending on the temperature. 2 The decomposition is spontaneous only at high temperature. 3 The entropy change is negative. A 1 and 2 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3

6 9729/01/H2 10 The reaction between NO and Br2 is proposed to proceed via the following mechanism: Step 1: NO + Br2 NOBr2 (fast) Step 2: NOBr2 + NO 2NOBr (slow) Which statements are correct? 1 NOBr2 is a radical. 2 The rate equation for this reaction is rate = k[Br2][NO]2. 3 NOBr2 is formed at the transition state. A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 1 only 11 The kinetics of the following reaction is investigated, and the experimental data is given in the table below. 2R + 2S ⎯→ T + U [R] / mol dm−3 [S] / mol dm−3 initial rate / mol dm−3 s−1 0.015 0.010 5.10  10−4 0.030 0.020 4.08  10−3 0.045 0.010 1.53  10−3 What is the numerical value of the rate constant for this reaction? A 0.00294 B 3.40 C 227 D 340

7 9729/01/H2 [Turn over 12 Ethanol is produced industrially by reacting ethene and steam. C2H4(g) + H2O(g) ⇌ C2H5OH(g) H = –50.3 kJ mol–1 Kp has a value of 1.8 × 10–5 and the partial pressures of the reactants at equilibrium are shown. reactant partial pressure / x 106 Pa ethene 4.8 steam 2.8 Which statement is correct? A Adding a catalyst increases the value of Kp for the reaction at equilibrium. B The overall process is a nucleophilic addition reaction. C Increasing the temperature will increase the Kp for the reaction. D Partial pressure of ethanol at equilibrium is 242 x 106 Pa. 13 Lithium reacts with nitrogen at room temperature to form solid Li3N. Three vessels of equal volume are connected by taps 1 and 2 as shown. At the start, taps 1 and 2 are closed, the left -hand vessel is evacuated, the middle vessel has the indicated reaction at equilibrium and the right-hand vessel contains lithium only. Which action would allow the equilibrium mixture to contain the most ammonia? A Keep both taps 1 and 2 closed. B Open both taps 1 and 2. C Open tap 1 only. D Open tap 2 only. evacuated N2(g) + 3H2(g) ⇌ 2NH3(g)

8 9729/01/H2 14 The table below describes some indicators. indicator colour in acid colour in alkali pKa range of pH for colour change methyl orange red yellow 3.7 3.2 − 4.4 thymol blue yellow blue 8.9 8.0 − 9.6 For the titration of NaOH(aq) against HCOOH(aq), which row shows the most suitable indicator and the corresponding colour change? indicator colour change A methyl orange red to orange B methyl orange yellow to orange C thymol blue yellow to green D thymol blue blue to green 15 In this question, Q represents an atom of chlorine, bromine or iodine. Which statement about their atoms, molecules or halide ions is correct? A Down the Group, p ermanent dipole–permanent dipole forces between halogen molecules become stronger. B The first ionis