2021 VJC Prelim P1 Qns

1  VJC 2021 8873/01/PRELIM [Turn over VICTORIA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 1 CHEMISTRY 8873/01 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.

2  VJC 2021 8873/01/PRELIM [Turn over This document consists of 11 printed pages and 1 blank page. For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 What is the electronic configuration of Cu+ ion, with proton number 29? A 1s22s22p63s23p63d10 C 1s22s22p63s23p63d84s2 B 1s22s22p63s23p63d94s1 D 1s22s22p63s23p63d84p2 2 Use of the Data Booklet is relevant to this question. The ion X+ has 54 electrons and 78 neutrons. Which of the following statements are incorrect? 1 The fluoride of X formed is expected to have a higher melting point than NaF. 2 The first ionisation energy of element X is lower than that of Fr. 3 In an electric field, the ion X+ will be deflected at a larger angle than that of Na+. A 1, 2 and 3 C 2 and 3 only B 1 and 2 only D 3 only 3 To produce decaffeinated coffee, pure liquid CO2 is sometimes used to extract caffeine from coffee beans. caffeine The solubility of caffeine greatly increased when a mixture of ethanol and liquid CO 2 (ethanol−CO2 mixture) was used. Which interaction best explains why caffeine is more soluble in the ethanol−CO2 mixture as compared to liquid CO2? A instantaneous dipole–induced dipole interactions B permanent dipole–permanent dipole interactions C dative covalent bonding D hydrogen bonding

3  VJC 2021 8873/01/PRELIM [Turn over 4 In which pair does compound X have a higher boiling point than compound Y? compound X compound Y A CH3CO2NH4 CH3CH2NH2 B PH3 PCl3 C CH3COCH3 CH2=CHCH2OH D SiCl4 SiO2 5 The Brønsted–Lowry theory describes acid and base character. When concentrated sulfuric acid and concentrated nitric acid are mixed, the following reactions occur. H2SO4 + HNO3 ⇌ HSO4– + H2NO3+ H2NO3+ ⇌ H2O + NO2+ H2O + H2SO4 ⇌ HSO4– + H3O+ Which species are Brønsted–Lowry bases in these reactions? 1 HSO4– 2 H2NO3+ 3 H2O A 1, 2 and 3 C 2 and 3 only B 1 and 3 only D 2 only 6 10 cm3 of 0.0250 mol dm–3 of hydrochloric acid was mixed with 10 cm 3 of 0.0500 mol dm–3 of sodium hydroxide. What is the pH of the resulting solution? A 1.9 B 7.0 C 12.1 D 13.7 7 Which option consists of an acid buffer? A 20 cm3 of 0.100 mol dm−3 HCl and 10 cm3 of 0.100 mol dm−3 KOH B 20 cm3 of 0.100 mol dm−3 CH3COOH and 10 cm3 of 0.100 mol dm−3 Ba(OH)2 C 10 cm3 of 0.100 mol dm−3 H2SO4 and 40 cm3 of 0.100 mol dm−3 NH3 D 10 cm3 of 0.100 mol dm–3 CH3COOH and 5 cm3 of 0.100 mol dm–3 NaOH 8 In the preparation of silicon, silicon dioxide is heated with magnesium. SiO2 + 2Mg → 2MgO + Si

4  VJC 2021 8873/01/PRELIM [Turn over The product mixture contains MgO and Si only. To separate the silicon from the product mixture, a student proposed the following two possible methods. 1. Heat the mixture gently and collect the silicon vapour. 2. Shake the mixture with aqueous hydrochloric acid and filter. Which of the methods will not work? A 1 only B 2 only C 1 and 2 D none 9 The information relates to element Z. ● Z is a Period 3 element. ● A Z atom has a half-filled subshell in its ground state. ● The chloride of Z forms an acidic solution in water. What could Z be? A Na B Si C P D Cl 10 Use of the Data Booklet is relevant to this question. Which of the following statements about iodine and its compounds are correct? 1 Hydrogen iodide is a stronger acid than hydrogen bromide as the H–I bond is weaker. 2 When aqueous chlorine is added to potassium iodide and the aqueous mixture is shaken with tetrachloromethane, a purple organic layer is obtained. 3 Hydrogen iodide has a higher boiling point than hydrogen chloride due to stronger instantaneous dipole-induced dipole interactions. A 1, 2 and 3 C 2 and 3 only B 1 and 3 only D 1 only 11 10 cm3 of a hydrocarbon CxHy was exploded in 100 cm3 of oxygen gas and cooled to room temperature. There was a contraction of 30 cm 3. When the resulting gas was passed through a solution of sodium hydroxide, there was a further contraction of 40 cm 3. All volumes measured are under room conditions. What is the molecular formula of the hydrocarbon? A C4H8 B C4H10 C C5H10 D C5H12 12 10 cm3 of 0.2 mol dm–3 XO42– reacts completely with 40 cm3 of 0.1 mol dm–3 iron(II) sulfate solution. If Fe2+ is oxidised to Fe3+ in the above reaction, what is the final oxidation state of X? A +2 B +3 C +4 D +5

5  VJC 2021 8873/01/PRELIM [Turn over 13 Use of the Data Booklet is relevant to this question. Butane is used as a fuel for cooking. When 0.025 mol of butane was burnt under a vessel containing 250 g of water, it was found that the temperature of the water rose by 50 ºC. Given that the heat transfer was 75% efficient, what is the enthalpy change of combustion of butane? A –18000 kJ mol–1 C –2090 kJ mol–1 B –2790 kJ mol–1 D –697 kJ mol–1 14 The following energy cycle and enthalpy changes are provided. ∆H / kJ mol–1 K(s) → K+(aq) + e– –251 P(s) + 2O2(g) + 3e– → PO43– (aq) –1284 K3PO4(s) → 3K+(aq) + PO43–(aq) –2 ∆Hf(K3PO4(s)) 3K(s) + P(s) + 2O2(g) K3PO4(s) 3K+(aq) + 3e– + P(s) + 2O2(g) 3K+(aq) + PO43–(aq) What is the enthalpy change of formation of solid potassium phosphate, ∆Hf(K3PO4(s))? A –1533 kJ mol–1 C –2035 kJ mol–1 B –1537 kJ mol–1 D –2039 kJ mol–1 15 Compound M, CH3CH=CHCHClCH3, reacts readily with alcoholic KCN. CH3CH=CHCHClCH3 + CN– → CH3CH=CHCH(CN)CH3 + Cl– The initial rate of this reaction was measured using different concentrations of compound M and CN– and the following results were obtained. experiment [M] [CN–] relative rate

6  VJC 2021 8873/01/PRELIM [Turn over / mol dm3 / mol dm3 1 0.1 0.1 1 2 0.2 0.1 2 3 0.3 0.3 3 Which conclusion could be drawn from the information? A The overall order of reaction is 2. B It is an addition reaction involving two reactant particles combining to form products. C The rate of reaction will increase when concentration of CN– increases. D The rate of reaction will change when chlorine atom in M is replaced with bromine. 16 The age of rock samples can be calcu