NJC Prelims Paper 1 QP

NJC/H2 Chem Preliminary Examination/02/2021 1 [Turn over NATIONAL JUNIOR COLLEGE SH2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER CHEMISTRY Paper 1 Multiple Choice Additional Materials: Optical Answer Sheet Data Booklet 9729/01 15 September 2021 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, subject class and registration number on the Answer Sheet in the spaces provided unless this has been done for you. 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. Instructions on how to fill in the Optical Mark Sheet Shade the index number in a 5 digit format on the optical mark sheet: 1st digit and the last 4 digits of the Registration Number. Example: Student Examples of Registration No. Shade: 2005648 25648 This document consists of 12 printed pages.

NJC/H2 Chem Preliminary Examination/02/2021 2 1 A sample of element sulfur contains four isotopes of the following composition. relative isotopic mass relative abundance 32 95.02 33 0.76 34 4.20 36 0.02 What is the relative atomic mass of sulfur in this sample? A 32.07 B 32.08 C 32.09 D 32.10 2 When 15 cm3 of a gaseous organic compound were completely burnt in an excess of oxygen, 30 cm3 of carbon dioxide and 15 cm3 of nitrogen were formed, all volumes being measured at the same temperature and pressure. Which could be the formula of the organic compound? A C2H4N2 B C2H7NO C C3H7NO D C3H6N2 3 Which ion has less electrons than neutrons and less neutrons than protons? ion neutrons nucleons A A− 18 37 B B2+ 17 34 C C3+ 16 33 D D3− 16 31 4 Covalent bonds are formed by orbitals overlap. CC C CH3 H H CC H H H1 2 3 4 5 6 Which statement does not describe the molecule above? A The V bond between C1–C2 is formed by 2sp2–2sp2 overlap. B The V bond between C2–C3 is stronger than that between C5–C6. C The S bond between C4–C5 is formed by 2sp–2sp2 overlap. D The V bond between C6–H is formed by 2sp3–1s overlap.

NJC/H2 Chem Preliminary Examination/02/2021 3 [Turn over 5 Which options contain a polar and a non-polar molecule? 1 CO2, H2O 2 SO2, PCl5 3 CH2Cl2 , SiCl4 A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 1 only 6 The value of pV is plotted against p for two gases, an ideal gas and a non-ideal gas, where p is the pressure and V is the volume of the gas. Which gas shows the greatest deviation from ideal gas behaviour at 200 qC? A CO2 B Cl2 C CH3OH D N2H4 7 Astatine is an element in Group 17. Which statements are correct? 1 Silver astatide is insoluble in aqueous ammonia. 2 Hydrogen astatide is less stable to heat than hydrogen iodide. 3 Astatine is more electronegative than iodine. A 1, 2 and 3 B 2 and 3 only C 1 and 2 only D 1 only Non-ideal gas pV p Ideal gas

NJC/H2 Chem Preliminary Examination/02/2021 4 8 The graph below shows the variation in the boiling point for 8 consecutive elements in the Periodic Table, all with atomic number ≤ 20. What can be deduced from the graph? A The ions of A and E are isoelectronic. B The chlorides become less acidic from A to C. C When the oxide of D is added to water, the resulting solution has a pH greater than 7 D The oxide of A reacts with excess aqueous sodium hydroxide to form a soluble complex. 9 Given the following data: Lattice energy of magnesium chloride –2526 kJ mol–1 Standard enthalpy change of hydration of chloride –384 kJ mol–1 Standard enthalpy change of hydration of magnesium –1890 kJ mol–1 What would be the change in temperature measured when 0.49 g of magnesium chloride was dissolved in 50 g of water? [Molar mass of MgCl2 = 95.3 g mol−1] A − 6.2 qC B − 3.3 qC C + 3.3 qC D + 6.2 qC

NJC/H2 Chem Preliminary Examination/02/2021 5 [Turn over 10 Combustion of carbon monoxide to form carbon dioxide is an exothermic reaction. What can be deduced from this information? 1 CO2 is more stable than CO. 2 The standard enthalpy change of formation of carbon dioxide is more exothermic than the standard enthalpy change of formation of carbon monoxide. 3 Combustion of CO has a low activation energy. A 1, 2 and 3 B 2 and 3 only C 1 and 2 only D 1 only 11 What can be concluded about the values of ¨H and ¨S from this graph? ∆H ∆S A positive positive B positive negative C negative positive D negative negative

NJC/H2 Chem Preliminary Examination/02/2021 6 12 Compound G is formed during a reaction involving only gaseous particles. The graphs below show how the percentage of compound G at equilibrium varies with temperature and pressure. Which equation represents the formation of compound G? equation ∆H A E(g) + 3F(g) 2G(g) negative B 2E(g) F(g) + 2G(g) positive C 4D(g) + 3E(g) 2F(g) + 6G(g) negative D E(g) + F(g) 2G(g) positive 13 Which reactions show NH3 behaving as a Lewis base? 1 HNO3 + NH3 o NH4NO3 2 2NH3 o NH2– + NH4+ 3 BH3 + NH3 o BH3NH3 A 1, 2 and 3 B 2 and 3 only C 1 and 2 only D 1 only 14 The auto-ionisation of H2O is an endothermic process. H2O(l) H+(aq) + OH–(aq) Kw = 1.0 × 10–14 at 25 qC Which option is correct about water at 60 qC? A pH < 7 B pH = 7 C [H+] > [OH−] D [H+] < [OH−]

NJC/H2 Chem Preliminary Examination/02/2021 7 [Turn over 15 A 1 dm3 solution contains 2 × 10−4 mol dm−3 each of magnesium, strontium, iron(II) and silver(I) ions. Which carbonate will be precipitated first when 1 mol dm−3 sodium carbonate is added dropwise into the solution? compound Ksp A Magnesium carbonate 1.3 × 10−7 mol2 dm−6 B Strontium carbonate 9.3 × 10−10 mol2 dm−6 C Iron(II) carbonate 2.1 × 10−11 mol2 dm−6 D Silver(I) carbonate 8.1 × 10−12 mol3 dm−9 16 Ethyl ethanoate undergoes an acid-catalysed hydrolysis in water where the concentration of acid in the solution remains constant. CH3CO2CH2CH3 + H2O o CH3CO2H + CH3CH2OH The rate equation is found to be rate = k[CH3CO2CH2CH3][H+] In an experiment, when 0.01 mol dm−3 HCl was reacted with 0.10 mol dm−3 ethyl ethanoate, the half-life was found to be 42 min. In a second experiment, 0.02 mol dm−3 HCl was reacted with 0.40 mol dm−3 ethyl ethanoate. What is the half-life of the second experiment? A 6.25 min B 10.5 min C 21 min D 42 min 17 What is the rate equation for the reaction with the mechanism shown? 2A A2 fast A2 + B o A2B slow A2B + B o A2B2 fast A Rate = k[A]2 B Rate = k[A][B] C Rate = k[A2][B] D Rate = k[A]2[B] 18 Which species is the weakest oxidising agent under standard conditions? A Ag+ (aq) B Cu2+ (aq) C Fe2+ (aq) D H+ (aq) H+

NJC/H2 Chem Preliminary Examination/02/2021 8 19 Each gold medal awarded in the Olympic Games weighs 500 g. The gold plating constitutes 1.2% by mass of the gold medal. The core of the medal is immersed in a solution of gold(III) chloride and connected to a power source wit