2022 WSS Chem Prelims P1

Name: ( ) Class: WHITLEY SECONDARY SCHOOL A Caring and Learning Community of Leaders Perseverance * Respect * Integrity * Discipline * Empathy PRELIMINARY EXAMINATION 2022 READ THESE INSTRUCTIONS FIRST Write your name, class and index number in the spaces at the top of this page. Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, class and index number on the Answer Sheet in the spaces provided unless this has been done for you. There are forty questions. 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. A copy of the Periodic Table is printed on page 15. The use of an approved scientific calculator is expected, where appropriate. This paper consists of 15 printed pages and 1 blank page SUBJECT : Chemistry (6092/01) LEVEL : Secondary 4 Express DATE : 29 August 2022 DURATION : 1 hour SETTER : Ms Ng Soo Hoon VETTERS : Ms Charlene Lye and Mr Ng Mun Leong ���

2 1 A gas turns moist blue litmus paper red, is soluble in water and is less dense than air. Which diagram shows a correct way of drying and collecting the gas? ���

3 2 A mixture of sand and sodium chloride can be separated in three steps. Step 1 is to add water to the mixture. The diagram shows Steps 2 and 3. Where is pure sodium chloride collected? 3 A gaseous mixture is made up of nitrogen, oxygen and nitrogen monoxide. Which diagram could show a pure sample of this mixture? ���

4 4 A beaker of an unknown gas Y was inverted over a porous pot containing carbon monoxide as shown. The apparatus was left for a while but the water level did not change. The gas Y could have been A ammonia. B carbon dioxide. C chlorine. D nitrogen. 5 The boiling points of some gases are given in the following table. gases boiling point /oC nitrogen xenon oxygen −196 −108 −183 A mixture of liquid oxygen, nitrogen and xenon at −200 oC was heated up by 15 oC. Which of the substances will still be in the liquid state at this higher temperature? A nitrogen only B xenon only C a mixture of nitrogen and oxygen D a mixture of oxygen and xenon ���

5 6 An element, R, has p protons and n neutrons in its nucleus. Which of the following gives a possible correct number of protons, neutrons and electrons in a negative ion of an isotope of R? protons neutrons electrons A p n + 1 p + 1 B p n + 1 p − 1 C p + 1 n p + 1 D p + 1 n p − 1 7 Which statement explains why potassium chloride, KCl, has a lower melting point than calcium oxide, CaO? A Potassium is more r