NJC 2019 H1 Promo Paper 1 (QP)

1 NJC Promotional Examination 8873/01/2019 [Turn over NATIONAL JUNIOR COLLEGE SH1 PROMOTIONAL EXAMINATIONS Higher 1 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER CHEMISTRY Paper 1 Multiple Choice Additional Materials: Optical Answer Sheet Data Booklet 8873/01 Tuesday 1 Oct 2019 40 minutes READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, subject class and registration number on the Answer Sheet in the spaces provided unless this has been done for you. There are 20 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. 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 10 printed pages and 0 blank page.

2 NJC Promotional Examination 8873/01/2019 [Turn over 1 Use of the Data Booklet is relevant to this question. What is the number of atoms in 500 cm3 of oxygen under room conditions? A 1.25 × 1022 B 1.34 × 1022 C 2.50 × 1022 D 2.68 × 1022 2 Gallium nitride, GaN, could revolutionise the design of electric light bulbs because only a small length used as a filament gives excellent light at low cost. GaN is an ionic compound containing the Ga3+ ion. Which statements about GaN are correct? 1 The outer electronic configuration of Ga atom is 4s24p1 since Ga is a Group 13 element. 2 The electron arrangement of the nitrogen ion in GaN is 1s2 2s2 2p3. 3 Ga3+ ion deflects less than Al3+ ion in an electric field. A 1 only B 2 only C 1 and 3 only D 2 and 3 only 3 Oxygen has two isotopes, 16O and 18O. An oxide ion, 𝑂8 𝑥 y–, has the same number of neutrons and electrons. What could be the values of x and y? x y A 16 1 B 16 2 C 18 1 D 18 2 4 Methyl mercaptan, CH3SH, is a substance often used to impart a smell to natural gas in a pipeline. The chemical equation for the combustion of CH3SH is as shown below. CH3SH + 3O2 → CO2 + SO2 + 2H2O A 10 cm3 sample of CH3SH is exploded with 60 cm3 of oxygen and the resultant gas mixture is passed into excess NaOH(aq). What is the percentage of the volume of the resultant gas mixture dissolved in NaOH? [All gas volumes are measured at room temperature and pressure.] A 40.0% B 28.5% C 20.0% D 14.3%

3 NJC Promotional Examination 8873/01/2019 [Turn over 5 Which sketch show the correct trend in the stated property for the elements in Period 3 of the Periodic Table? 1 atomic radius 2 first ionisation energy 3 electrical conductivity