SAJC 2022 P1 QP

1 [TURN OVER ST ANDREW’S JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATIONS HIGHER 2 CANDIDATE NAME CLASS 2 1 S CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Data Booklet 9729/01 15 September 2022 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name and class on the Answer Sheet in the spaces provided. 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. 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 19 printed pages (including this cover page) and 1 blank page.

2 [TURN OVER 1 Use of the Data Booklet is relevant to this question. Which statements about chromium and its compounds are correct? 1 The valence electronic configuration of Cr contains both an unpaired s electron and an unpaired p electron. 2 One of the 3d orbitals in chromium atom has only 2 lobes. 3 There are 58 electrons and 60 neutrons in the 52Cr16O42− ion. A 1, 2, and 3 B 1 and 2 C 2 and 3 D 1 only 2 The following graph shows the second ionisation energy of eight consecutive elements in Period 2 and 3. Which of the options A, B, C or D is silicon? 3 Which option is correct? Molecule Planar Polarity A Xenon difluoride Yes Polar B Chlorine(I) oxide No Non-polar C Methanal Yes Polar D Dichloromethane No Non-polar 2nd IE Atomic number A B C D

3 [TURN OVER 4 Which statements about ethanoic acid are correct? 1 1 molecule of ethanoic acid has 4 lone pairs of electrons. 2 Gaseous ethanoic acid forms a dimer comprising of two hydrogen bonds within a ring of 8 atoms. 3 The CꟷC bond in ethanoic acid is formed from a sp3−sp2 orbital overlap. A 1, 2 and 3 B 1 and 2 C 2 and 3 D 1 only 5 Which description of Dalton’s law is correct? A Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. B The total pressure of a mixture of gases is equal to the sum of the partial pressures of those gases. C The partial pressure of a gas in mixture is given by the product of its mole fraction and the total pressure. D The partial pressure of a gas in a mixture is given by the product of its percent by mass and the total pressure.

4 [TURN OVER 6 Which graph shows the correct trends when the physical property of each of the elements Na, Al, Si and S is plotted against its atomic radius? A B C D 7 Which property describes the trend for the hydrogen halides as stated below? HCl > HBr > HI A thermal stability B boiling point C ease of oxidation D acidity

5 [TURN OVER 8 Use of the Data Booklet is relevant to this question. Which contains the largest number of molecules? A 810 cm3 of sulfur dioxide gas (measured at r.t.p.) B 1.56 g of methyl methanoate C 5.25 cm3 of ethanol where the density of ethanol is 0.755 g cm–3 D 1.70 x 1022 molecules of hydrogen peroxide. 9 Silane, SiH4, exists as a gas at standard temperature and pressure. Hess’ Law can be used to calculate the average Si–H bond energy in gaseous SiH4. Which information is needed to perform the calculation? A ∆Hformation(SiH4) only B ∆Hatomisation(Si), ∆Hatomisation(H), ∆Hformation(SiH4) C ∆Hcombustion(Si), ∆Hcombustion(H2), ∆Hcombustion(SiH4) D ∆Hcombustion(Si), ∆Hcombustion(H2), ∆Hformation(SiH4)

6 [TURN OVER 10 The decomposition of Arsine, AsH3, is catalysed by Arsenic, As, and can be represented by the following equation. AsH3 → As + 3 2 H2 Which graph does not describe the above reaction? A B C D 11 Steam reforming process is the most common method used for the industrial production of hydrogen. CH4(g) + H2O(g) CO(g) + 3H2(g) Kc = 6.50 mol2 dmꟷ6 What is the number of moles of steam used to react with 0.60 mol of methane, to form 0.90 mol of hydrogen in a 1 dm3 vessel? A 0.304 mol C 0.412 mol B 0.112 mol D 0.346 mol

7 [TURN OVER 12 Deuterium oxide, otherwise known as ‘heavy water’, consists of an oxygen atom bonded to two atoms of the hydrogen isotope, deuterium ( D2 1 ). Like water, deuterium oxide can undergo autoionisation. For D2O, we can use the term KD instead of KW. 2D2O D3O+ + ODꟷ The following graph show how the values of KW of H2O and KD of D2O vary with temperature. Which deduction is correct? A The enthalpy changes of autoionisation for both H2O and D2O are negative. B The extent of ionisation is smaller for D2O. C [OHꟷ] and [ODꟷ] decrease with increasing temperature. D OꟷD bond is weaker than OꟷH bond. 13.0 14.0 15.0 16.0 0 10 20 30 40 50 60 pKW or pKD Temperature / C D2O H2O

8 [TURN OVER 13 The numerical values of the solubility product of calcium hydroxide and calcium carbonate are 6.5 x 10ꟷ6 and 8.0 x 10ꟷ7 respectively at 25 ºC. Which statements are correct? 1 A precipitate is formed when equal volumes of 0.001 mol dm -3 calcium nitrate and a solution of pH 12.5 are mixed. 2 The solubility of calcium hydroxide in a solution of pH 12.5 is higher than the solubility of calcium carbonate in water. 3 The solubility product of calcium carbonate and calcium hydroxide decrease in a solution containing calcium nitrate. A 1, 2, and 3 B 1 and 2 C 2 and 3 D 2 only 14 How many stereoisomers does the following molecule have? O OH A 16 B 64 C 128 D 256

9 [TURN OVER 15 Rosmarinic acid can be found in herbs such as rosemary, sage and thyme. It has the following structure. OH OH O O O OH OH OH Which functional groups will remain in the product after rosmarinic acid reacts with excess hydrogen gas in the presence of platinum? 1 Alkene 2 Carboxylic acid 3 Ester 4 Phenol A 1 and 2 B 3 and 4 C 2, 3 and 4 D 4 only

10 [TURN OVER 16 Methylbenzene can undergo the following reaction. CH3 CH3 SO2Cl C SO Hl 3 + H2O Which statement about the mechanism of this reaction is correct? A The hybridisation states of the carbon atoms in benzene do not change during the reaction. B The  electron cloud of benzene will attack the O atom in ClSO3H. C The mechanism of this reaction is electrophilic addition. D The bond broken in ClSO3H is the S-O bond. 17 1-bromo-2,2-dimethylpropane, (CH 3)3CCH2Br, can be obtained from 2,2 -dimethylpropane, (CH3)4C, via free radical substitution with excess bromine. The yield however is low. What is the main reason for this? A Different mono-substituted products are formed. B The Br-Br bond requires a lot of energy to break. C (CH3)3CCH2Br is very unstable. D The bromine radical is regenerated during the formation of (CH3)3CCH2Br.