VJC 2021 Prelim H2P1 Qns [Final]

1 Ó VJC 2021 9729/01/PRELIM [Turn over VICTORIA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CHEMISTRY 9729//01 Paper 1 Multiple Choice 23 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 index number, name and CT group on the Answer Sheet. There are thirty questions. 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.

2 Ó VJC 2021 9729/01/PRELIM [Turn over For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 Use of the Data Booklet is relevant to this question. The ion X2+ has 53 electrons and 78 neutrons. Which of the following statements are incorrect? 1 X atom is isoelectronic with Xe. 2 The fluoride of X is expected to have a higher melting point than RbF. 3 The first ionisation energy of element X is lower than that of Fr. 4 In an electric field, the ion X2+ will be deflected at a smaller angle than that of Na+. A 1, 2 and 3 C 2 and 4 only B 1 and 4 only D 3 only 2 To produce decaffeinated coffee, the ethanol-CO2 mixture is used to extract caffeine from coffee beans. caffeine Which statement about caffeine is incorrect? A Caffeine is more soluble in the ethanol-CO2 mixture due to the hydrogen bond formed between ethanol and caffeine. B Caffeine molecule has a planar structure. C There are altogether 25 sigma bonds and 4 pi bonds in a caffeine molecule. D There are 5 carbon atoms which are sp2 hybridised.

3 Ó VJC 2021 9729/01/PRELIM [Turn over 3 In which pair does compound X have a higher boiling point than compound Y? compound X compound Y A CH3CO2NH4 CH3CH2NH2 B SiCl4 SiO2 C PH3 SiCl3H D Ni(OH)2 NiSO4 4 A vessel is made of an air-filled plastic and has a volume of 40.0 cm3. At 27 oC and 52.8 kPa, a slightly dented vessel of volume 38.5 cm3 is filled with air. To restore its original shape, the air inside the dented vessel is heated to a temperature of 60 oC. The pressure of air inside the vessel increases and creates a uniform outward force. Assuming that the air inside the vessel behaves ideally, what is the pressure of air inside the vessel at 60 oC when the shape is restored? A 56.4 kPa C 226 kPa B 113 kPa D 244 kPa 5 Elements Y and Z can be found in the third period of the Periodic Table. Two solutions were prepared by dissolving a chloride of Y and an oxide of Z in separate portions of water. Both solutions prepared can be used to dissolve Al2O3 but only one can be used to dissolve SiO2. What could Y and Z be? Y Z A silicon phosphorus B phosphorus sodium C magnesium phosphorus D sodium sulfur

4 Ó VJC 2021 9729/01/PRELIM [Turn over 6 The diagram represents the melting points of four consecutive elements in the third period of the Periodic Table. The sketches below represent another two properties of the elements. What could properties X and Y be? property X property Y A ionic radius effective nucleus charge B atomic radius electrical conductivity C number of valence electrons boiling point D electronegativity third ionisation energy Ÿ Ÿ Ÿ Ÿ proton number 0 melting point / K Ÿ Ÿ Ÿ Ÿ proton number 0 property Y Ÿ Ÿ Ÿ Ÿ proton number 0 property X

5 Ó VJC 2021 9729/01/PRELIM [Turn over 7 Use of the Data Booklet is relevant to this question. Which statement about Group 2 elements and their compounds is correct? A BaCl2 solution has a lower pH than that of MgCl2 solution. B The volume of gases formed per gram of carbonate decomposed increases down the group. C Strontium reacts more vigorously with cold water than magnesium since the standard reduction potential of strontium is more negative than that of magnesium. D Barium sulfate occurs naturally as a solid ore while magnesium sulfate occurs mainly in solution since barium sulfate has a strong crystalline lattice. 8 X2, Y2 and Z2 are Cl2, Br2 and I2 but not necessarily in the given order. The table below recorded observations when these halogens are separately added to aqueous solutions containing the halide ions followed by the addition of an organic solvent, CCl4. experiment reactants observation after shaking with CCl4 1 X2 (aq) + Y– (aq) Violet organic layer seen. 2 Z2 (aq) + X– (aq) Orange-red organic layer seen. 3 Z2 (aq) + Y– (aq) Violet organic layer seen. 4 Y2 (aq) + X– (aq) (Observations not recorded) Which information could be deduced from the above experiments? A HY has a lower boiling point that HX. B AgY(s) is soluble in excess dilute aqueous ammonia. C Ka value of HZ is larger than that of HY. D The colour of the organic layer in experiments 3 and 4 is the same.

6 Ó VJC 2021 9729/01/PRELIM [Turn over 9 Sodium percarbonate, (Na2CO3)x.y(H2O2) is a compound with both reducing and oxidising properties. It is present in some home and laundry cleaning products. 10.0 cm3 of 0.100 mol dm–3 sodium percarbonate releases 48.0 cm3 of carbon dioxide at room conditions on reaction with excess aqueous sulfuric acid. An identical sample, on titration with 0.0500 mol dm–3 KMnO4 in acidic medium, required 24.0 cm3 before the first pink colour appears. What is the ratio yx ? A 13 C 32 B 23 D 31 10 A flammable compound, with the formula CSz, burns in oxygen to give CO2 and SO2 as the only products. In a particular experiment, 20 cm3 of CSz vapour was completely reacted with 80 cm3 of oxygen. The volume of the gaseous mixture obtained after combustion was treated with excess aqueous sodium hydroxide. The volume of the gaseous mixture decreased to 20 cm3 after the treatment with sodium hydroxide. All measurements of volume were made at the same temperature and pressure, conditions under which CSz is a gas. What is the value of z? A 1 C 3 B 2 D 4

7 Ó VJC 2021 9729/01/PRELIM [Turn over 11 The enthalpy change of the following reaction between carbon and chromium(III) oxide is given: 3C(s) + Cr2O3(s) ® 2Cr(s) + 3CO(g) DHro = +790 kJ mol-1 In addition to DHro, one or more of the enthalpy changes listed below need to be known in order to calculate the enthalpy change of formation of Cr2O3. 1 enthalpy change of combustion of C 2 enthalpy change of atomisation of Cr 3 sum of the 1st, 2nd and 3rd ionisation energies of Cr 4 enthalpy change of combustion of CO Which are the enthalpy changes that need to be known? A 1, 2 and 3 only C 3 and 4 only B 1 and 4 only D 4 only 12 Instant ‘cold packs’ are used to relieve pain in ath