2021 MI Prelim H2 Chemistry P1 (9729_01) Answers

Class Adm No Candidate Name: This question paper consists of 12 printed pages and 2 blank pages. 2021 Preliminary Examination Pre-University 3 H2 CHEMISTRY 9729/01 Paper 1 Multiple Choice xxnd Sep 2021 1 hour Additional materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Do not turn over this question paper until you are told to do so Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, class and admission number in the spaces provided at the top of this page and on the Multiple Choice Answer Sheet 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 Multiple Choice Answer Sheet provided. Read the instructions on the Multiple Choice 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 question paper. The use of an approved scientific calculator is expected, where appropriate. FOR EXAMINER’S USE TOTAL (30 marks)

2 For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 Which of the following contains the same number of stated particles as the number of atoms in 19.0 g of fluorine gas? 1 Number of molecules in 2.0 g of hydrogen gas 2 Number of ions in 58.5 g of sodium chloride solid 3 Number of atoms in 14.0 g of nitrogen gas 4 Number of atoms in 12.0 g of graphite A 3 only B 1, 3 and 4 only C 2, 3 and 4 only D 1, 2, 3 and 4 Number of atoms in 19.0 g of fluorine gas = 1 mole of F atoms 🗸 1) Number of molecules in 2.0 g of hydrogen gas = 1 mole of H2 molecules ✗ 2) Number of ions in 58.5 g of sodium chloride = 2 moles of ions (both Na+ and Cl–) 🗸 3) Number of atoms in 14.0 g of nitrogen gas = 1 mole of N atoms 🗸 4) Number of atoms in 12.0 g of graphite solid = 1 mole of C atoms. 2 20 cm3 of an unknown hydrocarbon was completely combusted in excess oxygen gas. Upon cooling back to room temperature and pressure, the total volume of gases was 50 cm3 less than the initial total volume. After passing the remaining gases through KOH(aq), the volume of gases further decreased by 80 cm3. What is the molecular formula of the unknown hydrocarbon? A C2H4 B C4H4 C C4H6 D C4H8 CxHy + (x + y/4) O2 à xCO2 + (y/2) H2O Total vol / cm3 Initial vol / cm3 20 A 0 - A + 20 Change in vol / cm3 -20 -20x – 20y/4 +20x - Final vol / cm3 0 A – 20x – 5y 20x - A – 5y From qn, 80 cm3 of CO2 gas reacted with KOH(aq) 20x = 80 x = 4 From initial to final volume, volume dropped by 50 cm3 A + 20 – 50 = A – 5y 5y = 30 y = 6 Answer: C4H6

3 [Turn over 3 Which of the following statements is incorrect about the following reaction? 3VO2– + 2H+ → VO3– + 2VO + H2O A I