NYJC 2021 Prelim 9729 P1

[Turn Over This document consists of 14 printed pages.. NANYANG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CHEMISTRY 9729/01 Paper 1 Multiple Choice 21 September 2021 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, CT and NRIC / FIN on the Answer Sheet in the spaces provided. There are thirty questions in 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.

2 H2 Chemistry 9729/01 NYJC J2/2021 PRELIM. 1 The mass percentage of magnesium in a mixture of magnesium chloride and magnesium nitrate was found to be 21.25 %. What mass of magnesium chloride is present in 100 g of the mixture? A 47 g B 1 53 g C 56 g D 61 g 2 10.00 cm3 of 0.500 mol dm3 of a metal oxide, M2On, reacted exactly with 20.00 cm3 of 0.300 mol dm3 of acidified potassium manganate(VII) solution. Given that the oxidation state of M in the product is +6, what is the value of n? A 1 B 2 C 3 D 4 3 The first six ionisation energies of an element, Q, in kJ mol1 are shown. 660; 1267; 2218; 3313; 7863; 9500 What can be inferred from the data provided? A Q is a Period 3 element. B Q forms an oxide with a giant molecular structure. C Q is likely to form a chloride with the formula QCl4 when reacted with chlorine. D Q has a lower first ionisation energy than the element preceding it in the Periodic Table. 4 Which of the following statements are correct? 1 The van der Waals radius of chlorine is larger than the van der Waals radius of argon. 2 The boiling point of N2H4 is higher than CH3CH2CHO as hydrogen bonds between N2H4 molecules are more extensive than the hydrogen bonds between CH3CH2CHO molecules. 3 The carboncarbon bond length is longer in diamond than in graphite. A 1, 2 and 3 B 1 1 and 2 only C 2 and 3 only D 3 only

3 H2 Chemistry 9729/01 NYJC J2/2021 PRELIM. [Turn Over 5 What is the pressure (in Pa) of a sample of hydrogen gas that has density of 8 g m3 at 300 °C? A 5573 4 22.7 10 273 uu u B 573 8 22.7 100 273 uu u C 5273 8 22.7 10 573 uu u D 573 4 22.7 100 273 uu u 6 Given the following enthalpy changes, enthalpy change/ kJ mol1 N2(g) + 3H2(g) o 2NH3(g) –92 N2(g) + 4H2(g) + Cl2(g) o 2NH4Cl(s) –629 NH3(g) + HCl(g) o NH4Cl(s) –176 What is the standard enthalpy change of formation of gaseous hydrogen chloride? A –46.3 kJ mol1 B –92.5 kJ mol1 C –180 kJ mol1 D –361 kJ mol1

4 H2 Chemistry 9729/01 NYJC J2/2021 PRELIM. 7 Some ∆Hʅf values are given below. compound ∆Hʅf / kJ mol1 H2O(l) 286 CO2(g) 394 C6H12O6(s) 1273 The overall reaction in photosynthesis can be represented by the following equation. 6CO2(g) + 6H2O(l) o C6H12O6(s) + 6O2(g) Which of the following statements are correct? 1 The enthalpy change of the reaction is +2807 kJ mol1. 2 In the formation of products, the system becomes less disordered. 3 The reaction is not spontaneous at all temperatures. A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 1 only 8 The decomposition of a sample of H2O2 solution is a first order reaction with a rate constant of 7.70 x 104 s1. What is the initial concentration of the H2O2 solution, in mol dm3, if its concentration has dropped to 0.0315 mol dm3 in 80 min? A 0.109 B 1 0.158 C 1.01 D 1.27

5 H2 Chemistry 9729/01 NYJC J2/2021 PRELIM. [Turn Over 9 For the hydrolysis of methyl propanoate, CH3OCOCH2CH3, in dilute HCl, the following rates of reactions were measured at 25 °C. CH3OCOCH2CH3 + H2O ∏ CH3OH + CH3CH2CO2H experiment [methyl propanoate] / mol dm3 [HCl] / mol dm3 initial rate / mol dm3 min1 1 0.10 0.20 0.192 2 0.15 0.10 0.144 3 0.10 0.10 0.096 4 0.30 0.15 ? Which statements are incorrect? 1 The initial rate for experiment 4 is 0.432 mol dm3 min1. 2 The rate constant is 9.6 mol2 dm6 min1. 3 If the half-life of methyl propanoate in experiment 1 is 6 minutes, then the half-life of methyl propanoate in experiment 4 is 8 minutes. A 1, 2 and 3 B 2 and 3 only C 3 only D 2 only 10 At a total pressure of 1.0 atm and a temperature of 60 oC, dinitrogen tetraoxide is 50 % dissociated according to the following equation: N2O4(g) ∏ 2NO2(g) What is the value of the equilibrium constant, Kp, for the dimerisation of NO2 at 60 oC? A 2 3 B 1 3 4 C 4 3 D 3 2

6 H2 Chemistry 9729/01 NYJC J2/2021 PRELIM. 11 Nitrogen is discharged from wastewater treatment facilities into rivers and streams, usually as NH3 and NH4+. The fraction of the total nitrogen present in the water to be discharged as NH3 is defined as: 3 + 34 [NH ] [NH ]+[NH ] Given that the base dissociation constant, Kb of NH3 is 1.76 u 105 mol dm3, what is the fraction of the total nitrogen in the water to be discharged as NH3 at pH 7? A 9.94 x 101 B 5.00 x 101 C 5.65 x 103 D 1.76 x 103 12 Which solution’s pH will not change significantly when a small amount of alkali is added? 1 20 cm3 of 0.15 mol dm3 of ethanoic acid mixed with 10 cm3 of 0.20 mol dm3 of potassium hydroxide 2 10 cm3 of 0.25 mol dm3 of K2HPO4 mixed with 5 cm3 of 0.15 mol dm3 of KH2PO4 3 20 cm3 of 0.10 mol dm3 phenylalanine, NH2 OH O A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 only

7 H2 Chemistry 9729/01 NYJC J2/2021 PRELIM. [Turn Over 13 Which graph correctly shows the relative melting points of the elements Mg, Al, Si and P plotted against their relative first ionisation energies? A B C D 14 Which property of Group 2 elements (magnesium to barium) or their compounds increases with increasing proton number? A the first ionisation energies of the elements B the acidity of aqueous solutions of the chlorides C the solubility of Group 2 sulfates D the decomposition temperature of the carbonates first ionisation energy melting point Mg Al Si P first ionisation energy melting point Mg Al Si P first ionisation energy melting point Mg Al Si P first ionisation energy melting point Mg Al Si P

8 H2 Chemistry 9729/01 NYJC J2/2021 PRELIM. 15 Which trends concerning halogens from fluorine to iodine and their compounds are incorrect? 1 The volatility of hydrogen halides decreases down the group. 2 The thermal stability of hydrogen halides increases down the group. 3 The reducing power of halide ions increases down the group. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only 16 What is the total number of stereoisomers exhibited by the product formed when the following compound reacts with excess ethanolic sodium hydroxide? Cl Br OH Cl A 2 B 4 C 8 D 16 17 A non-cyclic organic molecule contains only carbon atoms, hydrogen atoms and one oxygen atom. The molecule is a ketone and contains a chiral carbon atom. How many carbon atoms can the molecule contain? 1 five 2 six 3 seven A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 3 only

9 H2 Chemistry 9729/01 NYJC J2/2021 PRELIM. [Turn Over 18 Both maleic acid and fumaric acid are org anic compounds with the formula HO2CCH=CHCO2H. Data about the acids are given below. pKa1 pKa2 boiling point / oC maleic acid 1.9 6.2 202 fumaric acid 3.0 4.4 522 Which of