2024 CGS Chemistry Prelim Paper 1_Mark Scheme

ANSWER KEY READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluids. Write your name, index number and class on the Answer Sheet in the spaces provided. DO NOT WRITE ON ANY BARCODES. 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 OTAS 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 19. The use of an approved scientific calculator is expected, where appropriate. This booklet consists of 19 printed pages, including the cover page. CRESCENT GIRLS’ SCHOOL SECONDARY FOUR PRELIMINARY EXAMINATION 2024 CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet 6092/01 28 August 024 1 hour

2 1 2 3 4 5 6 7 8 9 10 B C D C A C B A D B 11 12 13 14 15 16 17 18 19 20 C A D A C D C C A B 21 22 23 24 25 26 27 28 29 30 C A D C B B A D A B 31 32 33 34 35 36 37 38 39 40 C D A A B C C B B C 1 A student measures the rate of the reaction between marble chips, CaCO3, and dilute hydrochloric acid. CaCO3 + 2HCI → CaCl2 + CO2 + H2O Which diagrams show apparatus that are suitable for this experiment? A 1 and 2 B 1, 2 and 4 C 2 and 3 D 2, 3 and 4

3 2 Chromatograms of a urine sample using two different solvents are shown below. Based on the two chromatograms, which drug(s) is/are present in the urine sample? A drug P only B drug Q only C drugs P and Q only D drugs P, Q and R 3 Since the discovery of graphite, scientists have been able to extract a single layer of carbon atoms (known as graphene) and convert it to another material known as graphane by attaching one hydrogen atom to each carbon atom as shown below. Graphane has the same hexagonal-ring structure as graphene and retains most of its properties too. Which properties of graphene is not likely to be shared by graphane? A It is insoluble in water. B It is very strong. C It has a high melting point. D It is an electrical conductor.

4 4 An isotope of element Z has 20 neutrons and 17 protons. Which is the correct symbol for an ion of the isotope of element Z? A 𝐙𝟏𝟕 𝟏𝟖 + B 𝐙𝟏𝟕 𝟏𝟖 - C 𝐙𝟏𝟕 𝟑𝟕 - D 𝐙𝟏𝟖 𝟑𝟕 - 5 Hydrogen is able to form compounds with metals and non-metals. The formulae of some of these compounds are shown below. CH4 HCl MgH2 KH What is the order of melting point of these compounds? lowest melting point highest melting point