2023 MGS 6092 Prelim Chem P1, P2, MS

Page 2 of 17 Methodist Girls’ School Chemistry Sec 4 Preliminary Examination 2023 1 Ethylamine gas, C2H5NH2, and hydrogen chloride gas, HCl, react together to form a white solid, ethylamine hydrochloride. At which position in the tube would a ring of solid white ethylamine hydrochloride form? 2 Bromate ion, bromide ion and hydrogen ions react according to the equation shown. BrO3-(aq) + 5Br -(aq) + 6H+(aq) → 3Br2(aq) + 3H2O(l) Some apparatus for measuring the change in the rate of this reaction is suggested. 1 gas syringe 2 balance 3 pH meter Which apparatus is suitable to measure the rate of this reaction? A 1 only B 3 only C 1 and 2 D 2 and 3 3 Some substances may be separated using paper chromatography. The diagram shows the results of running two mixtures in a suitable solvent. Which spot has an R f value of 0.4? start line

Page 3 of 17 Methodist Girls’ School Chemistry Sec 4 Preliminary Examination 2023 4 The diagram shows the structural formula of methylamine. What is the total number of electrons involved and not involved in the bonding of methylamine molecule? Total number of electrons involved in bonding Total number of electrons not involved in bonding A 6 4 B 6 6 C 12 4 D 12 6 5 Both calcium chloride and potassium chloride are ionic compounds. Which statement about these compounds is correct? A Potassium chloride has a higher melting point than calcium chloride because the potassium ion has a greater charge than calcium ion. B Calcium chloride and potassium chloride conduct electricity because positive and negative ions flow through the solid material. C Molten calcium chloride has a greater electrical conductivity than molten potassium chloride because calcium contributes more electrons to the delocalised ‘sea of electrons’ than potassium. D In the calcium chloride lattice, the ratio of calcium ions to chloride ions is half that of the ratio of potassium ions to chloride ions in the potassium chloride lattice. 6 Which sample contains the same number of the named particles as the number of molecules in 35.5 g of chlorine? A atoms in 16 g of sulfur B atoms in 23 g of sodium C molecules in 32 g of methane D molecules in 88 g of carbon dioxide

Page 4 of 17 Methodist Girls’ School Chemistry Sec 4 Preliminary Examination 2023 7 Sodium carbonate reacts with dilute hydrochloric acid. Na2CO3 + 2HCl → 2NaCl + H2O + CO2 A sample containing 0.0800 mol of sodium carbonate is added to a solution containing 0.100 mol of hydrochloric acid. What volume of carbon dioxide is produced at room temperature and pressure? A 0.96 dm3 B 1.20 dm3 C 1.92 dm3 D 2.40 dm3 8 Which statement about acids and bases is correct? A A 0.1 mol/dm 3 solution of ethanoic acid has a higher pH than a 0.1 mol/dm 3 solution of hydrochloric acid. B All bases dissolve in water to produce OH– ions. C All oxides of non-metals are acidic in nature. D Bases react with nitrates to produce ammonia. 9 Two solutions are prepared. • Solution P is 0.050 mol/dm3 hydrochloric acid. • Solution Q is 0.100 mol/dm3 butanoic acid. A 2 cm strip of magnesium ribbon is put into 100 cm3 of each solution. Fizzing is seen in both solutions but the fizzing is faster in solution P than in solution Q. Which statement helps to explain this observation? A Magnesium reacts with solution P to form a salt, but does not form a salt with solution Q. B More particles are dissociated in solution P than are dissociated in solution Q. C Solution P is a strong acid while solution Q is a weak acid. D The particles are closer together in solution Q than they are in solution P.

Page 5 of 17 Methodist Girls’ School Chemistry Sec 4 Preliminary Examination 2023 10 Reactions 1, 2 and 3 are used in the manufacture of three fertilisers which are underlined in the equations. Reaction 1: H2SO4 + 2NH3 → (NH4)2SO4 Reaction 2: 2H2SO4 + Ca3(PO4)2 → Ca(H2PO4)2 + 2CaSO4 Reaction 3: 3H2SO4 + Ca3(PO4)2 + 6NH3 → 2(NH4)3PO4 + 3CaSO4 The relative molecular mass, M r, of sulfuric acid and of each fertiliser is shown in the table. H2SO4 (NH4)2SO4 Ca(H2PO4)2 (NH4)3PO4 Mr 98 132 234 149 In each reaction, 98 g of sulfuric acid was used. Which reaction gives the greatest and least mass of fertiliser? greatest mass least mass A 1 2 B 1 3 C 2 1 D 3 2 11 Tests were carried out on an aqueous solution of an unknown compound, P. The observations are recorded in the table. test observation aqueous sodium hydroxide added green precipitate, soluble in excess giving a green solution dilute nitric acid added then aqueous barium nitrate white precipitate dilute nitric acid added then aqueous silver nitrate no precipitate Which ions are present in P? A Cr3+ and Cl– B Cr3+ and SO42– C Fe2+ and Cl– D Fe2+ and SO42–

Page 6 of 17 Methodist Girls’ School Chemistry Sec 4 Preliminary Examination 2023 12 A sample of an alloy containing two metals was subjected to several tests as shown. Which two metals are present in the alloy? A iron and aluminium B iron and lead C iron and zinc D lead and zinc 13 The steps for the preparation of a pure sample of sodium nitrate are listed. 1 Titrate with dilute nitric acid until the end-point is seen. 2 Evaporate to concentrate the solution. 3 Rinse out the conical flask. 4 Add indicator. 5 Pipette a known volume of aqueous sodium hydroxide into a conical flask. 6 Cool and filter to remove crystals. 7 Repeat using the same volumes of aqueous sodium hydroxide and dilute nitric acid but no indicator. Which order of steps is correct? A 1 → 7 → 5 → 4 → 2 → 6 → 3 B 3 → 5 → 7 → 1 → 2 → 4 → 6 C 4 → 1 → 3 → 5 → 2 → 6 → 7 D 5 → 4 → 1 → 3 → 7 → 2 → 6

Page 7 of 17 Methodist Girls’ School Chemistry Sec 4 Preliminary Examination 2023 14 In each of three experiments, a halogen was added to separate solutions containing ions of one of the other two halogens. The table shows the results. Experiment Halogen added Solution of halide U- V- W- 1 U2 No reaction Reaction occurs 2 V2 Reaction occurs Reaction occurs 3 W2 No reaction No reaction What were the halogens U, V and W? U V W A Br2 Cl2 I2 B Br2 I2 Cl2 C Cl2 Br2 I2 D Cl2 I2 Br2 15 The table gives properties of four metals, P, Q, R and S. method of extraction reaction with water or steam reaction with acid P electrolysis only no reaction with water reacts slowly Q heating oxide with carbon reacts slowly with steam reacts slowly R electrolysis only reacts rapidly with steam reacts rapidly S heating oxide with carbon no reaction with water no reaction Which statement is correct? A P is the least reactive. B Q would displace R from a solution of its salt. C R could be zinc. D S could be copper.

Page 8 of 17 Methodist Girls’ School Chemistry Sec 4 Preliminary Examination 2023 16 The proton number of caesium is 55. Compared with lithium, the melting point of caesium is ......1...... and the reaction of caesium with water is ......2...... vigorous. The number of electron shells in caesium is ......3...... compared to lithium. Which words correctly complete gaps 1, 2 and 3? 1 2 3 A higher more the same B higher less greater C lower more greater D lower more the same 17 Chemical reactions occur in the blast furnace during the extraction of iron. Which of these types of reaction occur? 1 acid-base 2 combustion 3 redox A 1 and 2 only B 1 and 3 only C 1, 2 and 3 D 2 and 3 only 18 Attaching pieces of magnesium to underground iron pipes can protect the iron from corrosion. Which reaction protects the iron from corrosion? A Fe