2023 ACJC H2 Chem Prelim Paper 1 Worked Solutions

1 © ACJC 2023 9729/01/Prelim/2023 [Turn over Anglo-Chinese Junior College JC2 Preliminary Examination Higher 2 CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Data Booklet 9729/01 13 September 2023 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name and index number on the Answer Sheet in the spaces provided unless this has been done for you. There are thirty questions in this section. 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 xx printed pages and xx blank page.

2 © ACJC 2023 9729/01/Prelim/2023 [Turn over 1 Which types of chemical bonds listed below are present in solid ammonium nitrate? 1 ionic bonds 2 dative bonds 3 hydrogen bonds A 1 only B 1 and 2 only C 1 and 3 only D 1, 2 and 3 Ans: B Identify structure to be giant ionic, with covalent bonds within the polyatomic cation, NH4+, and polyatomic anion, NO3–. There is a dative covalent bond between N and H in NH4+, and N and O in NO3–. AOA 2 1.00 mol of gaseous molecules A take up a volume of 50 dm 3 at a pressure of 2 bar and a temperature of 50 oC. Which statements explain the above observation? 1 Gaseous molecules of A are in constant rapid random motion. 2 Gaseous molecules of A have significant molecular volume. 3 Gaseous molecules of A experience strong intermolecular forces of attraction. A 1 only B 1 and 2 only C 2 and 3 only D 1, 2 and 3 Ans: B For ideal gas, 𝑉𝑖𝑑𝑒𝑎𝑙 = 𝑛𝑅𝑇 𝑝 = 1.00×8.31×(273+50) 200 000 = 13.4 dm3 ∴ Vobserved > Videal All gases are in constant rapid random motion and exerts pressure as a result. Since there is a positive deviation (Vobserved > Videal), it is possibly due to significant molecular volume. Strong IMF would lead to a negative deviation. AOB

3 © ACJC 2023 9729/01/Prelim/2023 [Turn over 3 Two properties relating to silicon and sulfur which are non–metallic elements and their atoms are as follows. • property 1 – the oxide forms a strong acid in water • property 2 – no paired 3p electrons Which properties do silicon and sulfur have? silicon sulfur A 1 and 2 1 only B 1 and 2 1 and 2 C 2 only 1 only D 2 only 1 and 2 Ans: C Property 1 SiO2 does not dissolve in water because of strong covalent bonds between the Si and O atoms in the giant molecular structure. SO3 readily soluble to form an acidic solution. SO3(l) + H2O(l