2024 TJC Prelims H1 P1 QP

1 8873 / TJC Prelims / 2024 TEMASEK JUNIOR COLLEGE 2024 JC2 PRELIMINARY EXAMINATION Higher 1 CHEMISTRY 8873/01 Paper 1 Multiple Choice 12 September 2024 1 hour Additional Materials: Multiple Choice Answer Sheet (OMS) Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. There are thirty questions In this paper. Answer all questions. For each question there are four possible answers A, B, C, 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. Write your name & Civics Group on the Answer sheet. Shade your index number in the appropriate boxes. 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 12 printed pages. Write your name and Civics Group Index number (refer to entry proof)

2 8873 / TJC Prelims / 2024 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 (OMS). 1 Which statement about the electrons in a ground state nitrogen atom is correct? A There are more electrons in s orbitals than there are in p orbitals. B Electrons are present in two different energy levels. C There is a pair of electrons in one of the p orbitals. D The occupied orbital of highest energy is spherical. 2 In an experiment, protons are deflected by an angle of +10°. In another experiment under identical conditions, particle X is deflected by an angle of –2.5°. What could be the composition of particle X? protons neutrons electrons A 4 4 5 B 2 2 3 C 2 2 1 D 1 2 2 3 Which compound is composed of cation and anion that has the same number of electrons as each other? 1 Na2O 2 NaN3 3 NH4F 4 NaCl A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

3 8873 / TJC Prelims / 2024 [Turn over 4 Use of the Data Booklet is relevant to this question. The sixth ionisation energies of four different elements are shown below. The elements are arsenic, selenium, antimony and tellurium (though not necessarily in that order) from Groups 15 and 16. Which of the following shows the sixth ionisation energy of antimony? A 12300 B 10400 C 7880 D 6820 5 Which feature is present in each of the ions CO32– and SO32–? A All bond angles are 120° B One dative covalent bond C Three sigma bonds D Eight lone pairs of electrons 6 Beryllium chloride, BeCl2, fully reacts with ammonia, NH3 to form a compound. Which of the statements is incorrect? A The compound is formed from 1 mole of BeCl2 and 2 moles of NH3. B The Be-N bond formed is chemically similar to a covalent bond. C The beryllium atom in beryllium chloride is electron deficient. D The compound is capable of forming only two hydrogen bonds per molecule. 7 In which of the following pairs of compounds would the first compound have a higher melting point than the second compound? 1 Na2O, K2O 2 AlF3, AlCl3 3 MgO, MgCl2 A 1, 2 and 3 B 1 and 2 C 2 and 3 D 1 only

4 8873 / TJC Prelims / 2024 8 Trimethoprim (TMP) is used for the treatment of urinary tract infections. It has the following structure: Which are the correct bond angles w, x, y and z? w x y z A 90 180 120 90 B 90 105 118 107 C 109.5 105 120 107 D 109.5 180 118 120 9 Use of the Data Booklet is relevant to this question. A solution containing 25 cm3 of 0.1 mol dm-3 VO2+ reacts completely with 0.245 g of zinc. Which of the following can be the vanadium-containing species in the product? A VO3– B VO2+ C V3+ D V2+ 10 Which oxide does not react with dilute sodium hydroxide to produce a salt? A Al2O3 B P4O10 C SO2 D SiO2 11 When phosphoryl chloride, POCl3, dissolves in water, it gives a mixture of phosphoric acid and hydrochloric acid. How many moles of sodium hydroxide would be needed to neutralise the solution formed by adding one mole of POCl3 to excess water? A 3 B 4 C 5 D 6

5 8873 / TJC Prelims / 2024 [Turn over 12 The graph below shows the variation in the second ionisation energies for the consecutive elements Q to Z in the Periodic Table, all with proton number below 20. What can be deduced from the above? 1 T has a smaller atomic radius than U. 2 Effervescence is observed when a magnesium strip is dipped into the aqueous solution containing the chloride of element W. 3 When the oxide of U is mixed with water, an alkaline solution is formed. A 1, 2 and 3 B 1 and 2 C 2 and 3 D 3 only 13 Which sample contains the same number of the named species as the number of molecules in 1 g of hydrogen? A Electrons in 1 g of helium B Atoms in 23.0 g of sodium C Ions in 26.5 g of sodium carbonate D Molecules in 44 g of carbon dioxide 14 Use of the Data Booklet is relevant to this question. A sample of glass is composed of 50% SiO2, 38% CaO and 12% Al2O3 by mass. What is the Si / Al molar ratio in the glass sample? A 0.28 B 2.08 C 3.54 D 7.08

6 8873 / TJC Prelims / 2024 15 Hydrazine, N 2H4, was used as fuel for the Apollo space mission, and it can be synthesised in an environmentally friendly manner according to the following reaction. 2NH3(aq) + H2O2(l) N2H4(l) + 2H2O(l) substance ∆Hfo/ kJ mol–1 H2O(l) –286 N2H4(l) +51 NH3(aq) –80 H2O2(l) –174 Given the above enthalpy changes of formation, what is the enthalpy change of the above reaction in kJ mol−1? A −187 B −19 C +19 D +187 16 When 25 cm 3 of 1.0 mol dm −3 sodium hydroxide was neutralised with an equal volume of 0.5 mol dm−3 sulfuric acid, the temperature of the mixture rose by 7.0°C. What would be the temperature change if 50 cm3 of 0.5 mol dm−3 sodium hydroxide is neutralised with an equal volume of 0.25 mol dm−3 sulfuric acid? (Assume negligibe heat loss in each case.) A 1.8°C B 3.5°C C 7.0°C D 14°C

7 8873 / TJC Prelims / 2024 [Turn over 17 After the closure of a chemical plant in Switzerland, a substitution reaction between R and hydrogen sulfide ions is found to take place initial concentration of R / mol dm-3 initial concentration of hydrogen sulfide ions / mol dm-3 initial rate of reaction / mol dm-3 s-1 0.1 0.1 1.5 x 10-5 0.2 0.1 3.0 x 10-5 0.1 0.2 3.0 x 10-5 0.3 x 1.125 x 10-5 What conclusion can be drawn about the reaction? A The reaction is zero order with respect to the concentration of hydrogen sulfide ions. B The overall order of reaction is one. C The value of the rate constant is 1.5 x 10-4. D The value of x is 0.025. 18 Enzymes are biological catalysts, and many enzymes show specificity. An example is lipase which hydrolyses triglyceride molecules into glycerol and fatty acids. What does specificity mean in this context? A Lipase only works well over a narrow range of temperatures. B Lipase only works well over a narrow pH range. C Lipase only produces glycerol and fatty acids. D Lipase only hydrolyses triglycerides.

8 8873 / TJC Prelims / 2024 19 The kinetics of a reaction P → Q were investigated under different conditions. The following graph was obtained. Which of the following statements about the reaction is correct? A The unit of the rate constant is s-1. B A curve is obtained when [P] is plotted against time. C The same graph is obtained when the [P] is plotted against rate constant. D The rate constant remained unchanged when reaction is repeated at a higher temperature. 20 An enzyme, found in the stomach, operates at maximum efficiency when i