2022 QSS Chem Prelims P1

This document consists of 17 printed pages. Name: ………………………………………………….. ( ) Class: Sec 4A Queenstown Secondary School Preliminary Examination 2022 Secondary Four Express Chemistry 6092/01 31 August 2022 Time: 1200 – 1300h Wednesday Duration: 1 hour Additional Materials: Multiple Choice Answer Sheet READ THESE INSTRUCTIONS FIRST 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. 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 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 17. The use of an approved scientific calculator is expected, where appropriate. ���

2 Queenstown Secondary School [Turn over 1 Silica gel is a solid which can absorb water vapour from the air. It can be used to limit the growth of mould on leather goods and electronic equipment. Which of the following methods can be used to study the rate of absorption of water vapour in silica gel? A C B D 2 A liquid mixture contains methylbenzene and dilute aqueous copper(II) sulfate with different densities. Methylbenzene has a boiling point of 111oC and is insoluble in water. Which of the following steps can be used to obtain a liquid sample of methylbenzene and solid sample of copper(II) sulfate? step 1 step 2 A fractional distillation crystallisation B simple distillation evaporation C use a separating funnel crystallisation D use a separating funnel evaporation ���

3 Queenstown Secondary School [Turn over 3 During the test for chloride ion using aqueous silver nitrate, the solution must be acidified with dilute nitric acid. What is the purpose of adding dilute nitric acid? A To oxidise the chloride ion. B To increase the speed of reaction. C To prevent the precipitation of other ions. D To prevent the decomposition of silver chloride formed. 4 In an experiment, 4.0 cm3 of 1.0 mol/dm3 aqueous copper(II) sulfate and 8.0 cm3 of 1.0 mol/dm3 aqueous barium nitrate are mixed. CuSO4 (aq) + Ba(NO3)2 (aq) → Cu(NO3)2 (aq) + BaSO4 (s) What does the reaction vessel contain once the reaction is complete? A a colourless solution only B a white precipitate and a blue solution C a blue precipitate and a colourless solution D a white precipitate and a colourless solution 5 Two experimental set ups used to demonstrate diffusion of gases are shown in the diagrams below. The gases in each porous pot are ethene, C2H4, and oxygen, O2. In the first experiment, the gas introduced into the beaker is fluorine, F2, while in the second experiment, it is hydrogen, H2. ���

4 Queenstown Secondary School [Turn over What changes, if any, to the water levels X and Y would you expect to see in both experiments? experiment 1 experiment 2 A Y is higher than X Y is higher than X B X is higher than Y Y is higher than X C X and Y remain the same X is higher than Y D X and Y remain the same X and Y remain the same 6 Which of the following diagrams below best represents the relationship between the number of electrons in the valence shell of an atom and the number of hydrogen atoms which the atom is most likely to combine? A C B D ���

5 Queenstown Secondary School [Turn over 7 An element exists as 2 kinds of isotopes, P and Q. There are 80% of isotope P with a relative atomic mass of 45. If the relative atomic mass of the element is 47, what is the relative atomic mass of isotope Q? A 48 B 52 C 55 D 60 8 Which diagram represents the reaction between hydrogen and iodine that is not yet complete? A B C D 9 A compound G contains oxygen and one other element. Which property of G indicates that the bonds in G are ionic? A It is soluble in water. B It reacts with alkalis. C It has a low melting and boiling point. D It conducts electricity in the molten and aqueous states only. 10 The structural formula shows the bonding in pyrophosphoric acid. O O || || H – O – P – O – P – O – H | | O O | | H H What is the total number of bonding electrons for both phosphorus atoms in the formula? A 10 B 15 C 20 D 30 ���

6 Queenstown Secondary School [Turn over 11 Which substance in the table below could be methanol? substance melting point /oC boiling point /oC electrical conductivity in the liquid state in aqueous state A −114 −85 nil good B −98 65 nil nil C 180 218 nil nil D 420 970 good good 12 Solid silver metal, aqueous magnesium nitrate, solid graphite and molten sodium chloride conduct electricity. Which two of the substances conduct electricity as they contain mobile electrons? A solid silver metal and solid graphite B solid graphite and molten sodium chloride C solid silver metal and aqueous magnesium nitrate D aqueous magnesium nitrate and molten sodium chloride 13 40 cm3 of an aqueous 0.5 mol/dm3 solution of the hydroxide of metal X, exactly neutralises 80 cm3 of 0.25 mol/dm3 dilute sulfuric acid. What is the formula for the sulfate of X? A XSO4 B X2SO4 C X(SO4)4 D X2(SO4)3 14 A 400 g of sample of hydrated potassium sulfide crystals, K2S.xH2O, was heated to remove the water of crystallisation. The mass of solid that remained after heating was 220 g. How many moles of water are present in 1 mole of this compound? A 5 B 7 C 10 D 12 ���

7 Queenstown Secondary School [Turn over 15 Methane burns completely in oxygen according to the equation. CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (g) In an experiment, 40 cm3 of methane and 60 cm3 of oxygen are allowed to react in a closed vessel. The water vapour formed is allowed to condense. What is the volume of the resultant gaseous mixture when measured at room temperature and pressure? A 20 cm3 B 40 cm3 C 60 cm3 D 100 cm3 16 On adding 50 g of impure limestone, CaCO3 (Mr = 100), to excess hydrochloric acid, 6.0 dm3 of CO2 was evolved at room temperature and puressure. What is the purity of the limestone? A 25% B 50% C 75% D 100% 17 Four different solutions were electrolysed in s