2022 ZHSS Chem Prelims P1

1 [Turn over ZHONGHUA SECONDARY SCHOOL PRELIMINARY EXAMINATION 2022 SECONDARY 4E Candidate’s Name Class Register Number 4E CHEMISTRY 6092/01 26 Aug 2022 1 hour Additional Materials: OTAS READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, index number and class on the OTAS in the spaces provided. There are forty 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 OTAS. Read the instructions on the OTAS 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. A copy of the Periodic Table is printed on page 17. Setter: Ms Ong Lay Hong Vetter: Ms Julia Yeo This document consists of 17 printed pages, including this cover page. ���

2 [Turn over 1 The apparatus shown in the diagram was set up. The water level at X gradually moved up above the mark. When the water levels were observed to have stopped moving, the beaker of carbon dioxide were removed. The water level at X then fell below the mark before returning back to the mark. Which of the following is likely to explain why the water level at X fell below the mark? A Air inside the porous jar diffused out faster than the carbon dioxide. B Carbon dioxide in the porous jar diffused out slower than air which diffused in. C Air around the porous jar diffused in slower than the carbon dioxide diffused out. D Carbon dioxide around the porous jar continued to diffuse in faster than air diffused out. 2 The urine samples of athletes are routinely checked for the presence of drugs which can enhance their performance. The following diagram (not drawn to scale) shows a chromatogram of the urine sample of an athlete. He is suspected to have taken a banned drug with a retention value, Rf of 0.60. Which position, A, B, C or D indicates the presence of this drug? X carbon dioxide porous jar water air ���

3 [Turn over 3 The diagram below shows the fractional distillation of two liquids, R and S. R has a boiling point of 80 oC and S has a boiling point of 110 oC. Which statement(s) about the experiment is/are correct when the thermometer shows 80 oC? 1 The liquid left in the flask contains more S than R. 2 The vapour at point Y only contains R. 3 The temperature at X is higher than the temperature at Y. A 1 only B 1 and 2 C 2 and 3 D 1, 2 and 3 4 The diagram shows the outer shell electron arrangement of a molecule of a compound made up of the elements Z and Y. What is the formula of the compound formed between Z and magnesium? A MgZ B MgZ2 C Mg2Z3 D Mg3Z2 ���

4 [Turn over 5 Strontium is used in fireworks to produce crimson flames. The graph below shows the percentage abundance (%) and relative masses of three naturally occurring isotopes of strontium. What is the relative atomic mass of naturally occurring strontium? A 83.4 B 87.0 C 87.7 D 88.0 6 A radioactive isotope of thallium, 201Tl, is used to assess damage in heart muscles after a heart attack. 81 Which statement about 201Tl is correct? 81 A The isotope has a nucleon number of 120. B The number of electrons in one atom of this isotope is 81. C The number of neutrons in one atom of this isotope is 201. D 201 Tl is an isotope of 201 Tl 82 81 relative isotopic mass percentage abundance 85 86 87 88 ���

5 [Turn over 7 The table below shows the electronic configuration of elements W, X, Y and Z. W X Y Z 2.4 2.6 2.7 2.8.8.1 Which of the following formulae represent compounds with boiling points below room temperature? 1 WX2 2 XY2 3 Z2X A 1 and 2 B 1 and 3 C 2 and 3 D 1, 2 and 3 8 The following substances all contain covalent bonds. 1 ammonia 2 carbon dioxide 3 ethanol 4 diamond Which substances contain only single bonds? A 1 and 2 B 1 and 4 C 3 and 4 D 1, 3 and 4 9 In a pathology laboratory, a sample of urine containing 0.120 g of urea, NH2CONH2 was treated with an excess of nitrous acid. The urea reacted according to the following equation. NH2CONH2 + 2HNO2 à CO2 + 2N2 +3H2O The gas produced was passed through aqueous sodium hydroxide and the final volume measured. What was this final volume of gas left behind at room temperature and pressure? A 9.6 cm3 B 14.4 cm3 C 48.0 cm3 D 96.0 cm3 ���

6 [Turn over 10 Citric acid, the predominant acid in lemon juice, is a tribasic acid. A student titrated 25.0 cm3 samples of lemon juice with 0.55 mol/dm3 NaOH. The average titration volume was 29.50 cm3. The molar mass of citric acid is 192.12 g/ mol. What was the concentration of citric acid in the lemon juice? A 1.04 g/dm3 B 41.6 g/dm3 C 125 g/dm3 D 374 g/dm3 11 A washing powder contains sodium hydrogencarbonate, NaHCO3 as one of its ingredients. In a titration, a solution containing 1.00 g of the washing powder was found to react completely with 7.15 cm3 of 0.100 mol/dm3 of dilute hydrochloric acid. Assuming that sodium hydrogen carbonate is the only ingredient that reacts with the acid, what is the percentage by mass of sodium hydrogencarbonate in the washing powder? A 3.0 % B 6.0 % C 12.0 % D 24.0 % 12 Compound X has the molecular formula, Mn2O3. The following are some statements about compound X. • One mole of compound X contains 110 g of manganese and 48 g of oxygen. • The oxidation state of manganese is +2 in Mn2O3. • The charge of the oxide ion is -2. • The empirical formula of compound X is Mn2O3. • Three moles of oxygen molecules are needed to make one mole of compound X. How many statements about compound X are correct? A 2 B 3 C 4 D 5 13 Which equation suggests that a metal oxide, RO, behaves as an amphoteric oxide? A RO (s) + 2H+ (aq) à R2+ (aq) + H2O (l) B RO (s) + 2OH- (aq) à RO22- (aq) + H2O (l) C RO (s) + H2O (l) à R2+ (aq) + 2OH- (aq) D RO (s) + NH4+ (aq) à R2+ (aq) + H2O (l) + NH3 (g) ���

7 [Turn over 14 Which of the following does not show the appropriate reagents used for preparation of the named salts? salt reagents A barium sulfate barium nitrate + sulfuric acid B lead(II) chloride lead(II) carbonate + hydrochloric acid C lithium nitrate lithium hydroxide + nitric acid D magnesium chloride magnesium + hydrochloric acid 15 The following substances are used in the laboratory to test for the various ions and gases. acidifed potassium manganate(VII) aqueous ammonia aqueous barium nitrate aqueous silver nitrate red litmus paper limewater aqueous sodium hydroxide blue litmus paper wooden splint When testing for ammonia, chlorine, hydrogen and oxygen, what is the minimum number of items from the table above needed to identify these four gases? A 2 B 3 C 4 D 5 16 Solutions of 0.1 mol/dm3 Ca(NO3)2 and 0.1 mol/dm3 of Zn(NO3)2 undergo a series of reactions using pure reagents. Ca(NO3)2 + excess Na2CO3(aq) → L + excess HCl(aq) → M + excess NaOH(aq) → N Zn(NO3)2 + excess Na2CO3(aq) → X + excess HCl(aq) → Y + excess NaOH(aq) → Z L, M and N are calcium compounds. X, Y and Z are zinc compounds. How many of the L, M, N, X, Y and Z are white precipitate? A 2 B 3 C 4 D 5 ���

8 [Turn over 17 X, Y and Z are metals which form the cations X3+, Y2+ and Z+ respectively. Y2+ + Z → no visible cha